MANUAL 


OF 


SUGAB  ANALYSIS 


INCLUDING 


THE  APPLICATIONS  IN  GENERAL 


OP 


ANALYTICAL   METHODS  TO   THE   SUGAR  INDUSTRY. 


WITH  AN  INTRODUCTION 

OX  THE 

CHEMISTRY  OF  CANE  SUGAR,  DEXTROSE,  LEVULOSB,  AND 

MILK-SUGAR. 


UNIVE; 
BY 

J.    H.   TUCKEK,   PH.D. 

t  > 

SECOND  EDITION. 


NEW  YORK  : 
D.    VAN   NOSTRAND,    PUBLISHER, 

£3  MURRAY  STREET  AND  27  WARREN  STREET. 
1883. 


Copyright  by 

D.  VAN  NOSTRAND, 

1831. 


H.   J.    HEWITT,  PRINTER,  27  ROSE  STREET,  NEW  YORK. 


PREFACE. 


NOTWITHSTANDING  the  amount  and  variety  of  analytical 
work  required  for  the  various  interests  connected  with 
sugar,  there  exists  no  book  in  English  that  treats  of  this 
branch  of  analysis,  and  only  a  few  scattered  and  incom- 
plete dictionary  articles.  The  main  dependence  of  the 
chemist  must  be  on  German  and  French  sourees,  in  which 
languages  treatises  on  sugar  analysis  are  numerous. 

I  have  accordingly  attempted,  with  as  much  success  as 
may  be,  to  supply  this  deficiency  in  the  special  literature 
of  analytical  chemistry,  believing  that  there  is  now,  and 
still  more  in  the  near  future  there  will  be,  a  need  of  such 
a  work  in  English-speaking  countries. 

An  introduction  on  the  chemistry  of  the  more  important 
sugars  is  given,  on  account  of  its  intimate  connection  with 
the  subject ;  the  matter  is  brought  strictly  up  to  the  time 
of  publication,  and  in  some  important  respects — as,  for  ex- 
ample, in  relation  to  inversion,  and  the  melassigenic  action 
of  salts  on  cane-sugar — I  believe  to  be  more  full  than  can  be 
found  elsewhere. 

The  formulas  and  atomic  weights  used  are  according  to 

the  new  system,  and  the  temperatures  are  Centigrade. 

3 


4  PREFACE. 

I  desire  to  render  my  acknowledgments  to  Prof.  C.  F. 
Chandler,  of  Columbia  College,  New  York,  for  access  to 
his  fine  private  library  of  technical  chemistry ;  to  Dr.  A. 
Behr,  of  Jersey  City,  for  the  loan  of  books,  and  other 
favors  ;  and  to  W.  Baker,  Esq.,  Librarian  of  the  School  of 
Mines,  Columbia  College,  New  York,  for  uniform  courtesy 
and  help. 

THE  AUTHOR. 

XEW  YORK,  July    1881. 


CONTENTS. 


CHAPTER  I. 

THE  CHEMISTRY  OF  THE  SUGARS  AS  A  CLASS. 

The  Sweet  Taste,  9 — Chemical  Constitution,  10 — Classification,  12 — Formation 
in  Plants,  15 — Synthesis,  16 — Rotatory  Power,  17 — Fermentation:  mucous, 
18  ;  lactous,  19  ;  vinous,  21  ;  cellulosic,  25— Action  of  Heat,  26 — Oxidizing 
Agents,  26— Acids,  28— Saccharides,  28— Alkalies,  29. 

CHAPTER  II. 

CANE-SUGAR  OR  SACCHAROSE. 

Occurrence,  31 — Preparation  from  Natural  Sources,  84 — Physical  Properties, 
35 — Action  of  Light,  38— Composition,  39— Solubilities,  39 — Action  of 
Heat,  41 — Inversion  by  Heat,  43 — Inversion  by  Acids,  45 — Action  of  Sul- 
phuric Acid,  49 — Oxidizing  Agents,  50 — Alkalies,  54 — Sucrates  of  Potas- 
sium, 55  ;  Sodium,  56  ;  Calcium,  56  ;  Barium,  60  ;  Strontium,  61  ;  Iron, 
61  ;  Copper,  61;  Magnesium,  62 — Combination  of  Cane-Sugar  with  Neutral 
Salts,  62 — Melassigenic  Action  of  Salts,  64 — Various  Reactions,  72 — Para- 
saccharose,  72 — Inactive  Cane-Sugar,  73. 

CHAPTER  III. 

DEXTROSE,  LEVULOSE,  AND  INVERT-SUGAR. 

Dextrose,  74 — Formation,  75  —  Preparation,  75  —  Properties,  77  —  Rotatory 
Power,  78— Composition,  79 — Decompositions,  79 — Action  of  Alkalies,  80— 
Various  Reactions,  81 — Combinations,  83— Qualitative  Tests,  85 — Paradex- 
trose,  86. 

Levulose,  87 — Formation,  87 — Preparation,  87 — Properties,  88 — Decomposi- 
tions, 88 — Calcium  Compound,  89. 

Invert-Sugar,  89. 

CHAPTER  IV. 

LACTOSE  OR  MILK-SUGAR. 

Rotatory  Power,  91— Composition,  92— Solubilities,  92— Action  of  Heat,  92; 
of  Sulphuric  Acid,  93 — Alkalies,  94 — Fermentation,  95. 

5 


6  CONTENTS. 

CHAPTER  Y. 

DETERMINATION  OF  SPECIFIC  GRAVITY. 

The  Hydrostatic  Balance,  96— Mohr's  Balance,  96— The  Specific-Gravity  Flask, 
98 — Areometry,  100— Gay  Lussac's  Volumeter,  103 — The  Densimeter,  105 
— Baume's  Hydrometer,  106 — Balling's  or  Brix's  Areometer,  110 — Table 
showing  Sugar  Percentages,  Densities,  and  Baume  Degrees,  116-119. 

CHAPTER  VI. 

DETERMINATION  OF  CANE-SUGAR- OPTICAL  METHODS. 

Polarized  Light,  120 — Mitscherlich's  Saccharimeter,  126 — The  Soleil-Duboscq 
Saccharimeter,  130— Clerget's  Method,  136— Clerget's  Table,  141— The 
Soleil-Ventzko  Saccharimeter,  143 — Wild's  Polaristrobometer,  152 — Du- 
boscq's  Shadow  Saccharimeter,  157 — Schmidt  and  Haensch's  Shadow  Sac- 
charimeter, 159— Laurent's  Saccharimeter,  159 — The  Equivalence  of 
various  Saecharimeters,  163 — The  Decoloration  of  the  Sugar  Solution,  164 
—Errors  of  the  Optical  Method,  170— The  Optical  Inactivity  of  Invert- 
Sugar,  173 — Influence  of  various  Bodies  on  the  Optical  Estimation,  175 — 
Correction  of  Measuring  Apparatus,  177. 

CHAPTER  VII. 

DETERMINATION  OF  CANE-SUGAR— CHEMICAL  METHODS. 

Method  of  Peligot,  179— Extraction  by  Alcohol,  180  ;  by  Fermentation,  181— 
Estimation  after  Inversion,  by  Fehling's  Method,  182. 

CHAPTER  VIII. 

DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

Section  I.  Fehling's  Method  and  its  Modifications,  185— Part  I. :  The  Method 
as  suited  for  Technical  Work:  Volumetric,' 186— Fehling's  Solution,  187— 
Violette's  Solution,  188— Monier's  Solution,  188— Possoz's  Solution,  189— 
Calculation  of  Results,  191— Part  II. :  The  Method  as  suited  to  Exact 
Work  :  A.  Volumetric,  201  ;  B.  Gravimetric,  200— Mohr's  Method,  205. 

Section  II.  Determination  of  Dextrose  and  Invert-Sugar  by  other  Methods  than 
"that  of  Fehling  :  Knapp's  Method,  206— Sachsse's  Method,  207— Estima- 
tion of  Dextrose  and  Invert-Sugar  in  presence  of  each  other,  207— Estima- 
tion of  Lovuloso  and  Dextrose  in  presence  of  each  other,  208 — Gentele's 
Method,  210. 


CONTENTS.  7 

CHAPTER  IX. 

ANALYSIS  OF  KAW  SUGAR. 

Composition  of  Raw  Sugar,  211 — Estimation  of  Cane-Sugar,  213 — Estimation 
of  Invert-Sugar,  217;  of  Water,  217;  of  Ash,  222— Soluble  Ash,  224— 
Alkaline  Ash,  225— Sulphated  Ash,  226 — Estimation  of  Color,  229— Stam- 
mer's Colorimeter,  229— Estimation  of  Organic  Matter,  233 ;  of  Insoluble 
Matter,  236;  of  Yield,  237— Method  of  Coefficients,  237— The  Payen- 
Scheibler  Process,  240— Method  of  Dumas,  247. 

CHAPTER  X. 

ANALYSIS  OF  MOLASSES  AND  SYRUPS. 

Estimation  of  Cane-Sugar,  250;  of  Water,  252— Quotient  of  Purity,  253— Esti- 
mation of -Color,  258;  of  Alkalinity,  258. 

CHAPTER  XI. 

ANALYSIS  OF  THE  CANE  AND  CANE-JUICE. 

The  Cane,  260— Cane- Juice,  261— Estimation  of  Cane*- Juice,  Ventzke's  Me- 
thod, 262. 

CHAPTER  XII. 

ANALYSIS  OF  THE  BEET  AND  BEET-JUICE. 

The  Beet,  265— Scheibler's  Method  for  Estimating  the  Sugar,  266— Estimation 
of  Marc  and  Amount  of  Juice,  2G9 — Analysis  of  Beet-Juice,  270. 

CHAPTER  XIII. 

ANALYSIS  OF  WASTE  PRODUCTS. 

Analysis  of  Scums  and  solid  Residues,  273 — Refinery  Scum,  273 — Beet  Marc, 
275 — Carbonatation  Residues,  275 — Waste  Waters,  276 — Estimation  of 
.Cane-Sugar  in  very  dilute  Solutions,  276. 

CHAPTER  XIY. 

ANALYSIS  OF  COMMERCIAL  GLUCOSE  OR  STARCH-SUGAR. 

Composition,  278 — Estimation  of  Sugar  by  Fehling's  Method,  280;  by  Fermenta- 
tion, 281— Anthon's  Method,  282— Estimation  of  Water,  283— Adultera- 
tion of  Raw  Sugar  with  Dextrin,  284 — Detection  of  Starch-Sugar  when 
mixed  with  Refined  or  Raw  Cane-Sugars,  284— Chandler  and  Ricketts' 
Method,  287. 


8  CONTENTS. 

CHAPTER  XV. 

ESTIMATION  OF  MILK-SUGAR. 

By  Fehling's  Method,  290— Optically,  290. 

CHAPTER  XVI. 

ESTIMATION  OF  DEXTROSE  IN  DIABETIC  URINE. 
By  the  Optical  Method,  292— By  Fehling's  Method,  294. 

CHAPTER  XVII. 

THE  CHEMISTRY  OF  ANIMAL  CHARCOAL. 

Composition,  Analyses,  296— Mode  of  Action,  298 — Absorbing  .Power,  299 — 
Marks  of  good  Char,  303— Revivification,  303— Alteration  by  Use,  304— Car- 
bon, 306 — Carbonate  of  Lime,  306 — Alkaline  Salts,  307 — Sulphate  of  Lime, 
307— Iron,  307— Sulphide  of  Calcium,  308— Nitrogen,  309. 

*   CHAPTER  XVIII. 

THE  ANALYSIS  OF  ANIMAL  CHARCOAL. 

Estimation  of  Water,  311;  of  Carbon,  311;  of  Carbonate  of  Lime — Scheibler's 
Calcimeter,  313 — Calculation  for  Removal  of  Carbonate  by  Acid,  318 — 
Estimation  of  Calcic  Sulphate,  320;  of  Calcic  Sulphide,  321;  of  Calcic 
Phosphate,  322;  of  Iron,  323;  of  Soluble  Matter,  324;  of  Specific  Gravity, 
326;  of  Absorptive  Power,  327;  by  Dubosccfs  Colorimeter,  329 — Coren- 
winder's  Method,  332— The  Potash  Test,  333. 

APPENDIX. 

Note  on  the  Action  of  Organic  Matter  on  the  Alkaline  Solution  of  Cupric 
Oxide,  335- Tables,  338. 


CHAPTER  I. 

THE    CHEMISTRY   OF   THE   SUGARS    AS   A   CLASS. 

THE  term  sugar  is  applied  to  a  group  of  bodies  resem- 
bling each  other  by  a  number  of  striking  properties  ; 
these  properties — partly  chemical  and  partly  physical 
— are  as  follows :  (1)  the  sweet  taste ;  (2)  the  ability  to 
undergo  the  process  of  fermentation  ;  (3)  the  identity  or 
similarity  in  chemical  composition  or  relations ;  (4)  the 
power  that  aqueous  solutions  have  of  rotating  the  plane 
of  polarized  light ;  (5)  the  general  resemblance  in  physical 
and  chemical  characteristics,  such  as  their  ready  solubi- 
lity in  water,  insolubility  in  absolute  alcohol  and  ether, 
facility  of  crystallization  in  well-defined  forms,  the  simi- 
larity of  their  products  of  oxidation,  and  their  ability 
to  reduce  the  oxide  of  copper  in  alkaline  solution,  either 
directly  or  after  conversion  into  some  other  sugar  by  fer- 
mentation or  the  action  of  dilute  acids. 

The  sweet  taste  is  very  distinctive  of  sugars,  and  is 
possessed  in  a  greater  or  less  degree  by  nearly  all  of 
them,  from  cane-sugar,  which  is  the  type  of  sweet  sub- 
stances, to  some  of  the  rarer  saccharoids,  which  have 
this  property  in  a  very  low. degree  or  not  at  all.  The 
sugars  are  not  the  only  bodies,  however,  possessing  a 
sweet  taste,  as  glycol  and  glycerin  are  sweet,  as  well  as 
some  metallic  salts,  notably  the  acetates  of  lead ;  the 


10  CHEMISTRY  OF  THE  SUGARS  AS  A  CLASS. 

two  former  are,  however,  allied  to  the  sugars,  as  they 
are  polyatomic  alcohols.  The  yttria  salts  and  some  silver 
compounds  are  also  said  to  have  a  sugary  flavor.  The 
relative  sweetening  power  of  cane-sugar  to  dextrose  has 
been  generally  placed  as  two  to  one  ;  Parmentier  questions 
this,  and  gives  the  following  quantities  of  the  two  sugars 
as  having  an  identical  sweetening  effect : 

10  pts.  of  cane-sugar  to  40  pts.  of  water. 
12        "    dextrose     to  40    "  " 

It  has  been  asserted  that  levulose  is  sweeter  than  cane- 
sugar,  and  this  seems  to  be  confirmed  by  the  fact  that  in- 
vert-sugar is  sweeter  than  cane-sugar,  H.  Morton  placing 
the  excess  at  ten  per  cent. 

The  sugars  are  mostly  of  vegetable  origin,  though  a  few, 
as  inosite  and  dextrose,  are  found  in  animals  ;  they  exist  in 
a  great  variety  of  plants  distributed  over  every  part  of  the 
globe. 

CHEMICAL     CONSTITUTION. 

All  bodies  known  as  sugars  are  composed  of  carbon, 
oxygen,  and  hydrogen  ;  in  the  true  sugars  the  hydrogen 
and  oxygen  are  present  in  the  proportions  that  form  water. 
For  example,  dextrose  CGH12O,.,  has  the  hydrogen  and  oxy- 
gen present  in  the  exact  proportion  to  make  six  molecules 
of  water,  and  the  formula  may  be  written  thus  :  Cfi(H2O)6 ; 
the  compound,  from  this  point  of  view,  may  be  considered  as 
a  hydrate  of  carbon.  Bodies  thus  constituted  are  called 
carbohydrates,  and  under  this  name  are  included  many 
important  substances  not  classed  as  sugars,  though  sugar 
may  be  derived  from  many  of  them  by  the  action  of  dias- 
tase or  acids.  The  most  important  of  these  are  :  starch, 


CHEMICAL  CONSTITUTION.  H 

7iC6H10OB ;  cellulose,  7iC6H10O5 ;  gum,  C12H220U ;  and  dex- 
trin, C0H1005. 

Most  sugars  belong  to  the  class  of  the  hexatomic  alco- 
hols and  the  corresponding  ethers.  An  alcohol  is  a  com- 
pound in  which  hydrogen,  in  a  saturated  hydrocarbon,  is 
replaced  by  one  or  more  atoms  of  the  univalent  radical 
hydroxyl  HO ;  thus,  propenyl  alcohol  or  glycerin 
(C3H5)///(HO)3,  is  derived  from  the  hydrocarbon  propane 
C3H8  by  substituting  three  atoms  of  hydroxyl  for  the  same 
number  of  hydrogen,  the  result  being  a  triatomic  alcohol 
— that  is,  one  containing  three  atoms  of  hydroxyl  in  the 
place  of  an  equal  number  of  replaceable  hydrogen.  So 
with  higher  replacements  ;  mannite  C6H14O6,  may  be  consi- 
dered as  derived  from  the  saturated  hydrocarbon  C6H14  by 
replacing  six  atoms  of  hydrpgen  with  an  equal  number 
of  hydroxyl  atoms,  and  the  formula  may  be  written 
(C6H8)VI(HO)B,  which  represents  a  hexatomic  alcohol. 

Mannite  and  dulcite  are  important  representatives  of  the 
sugars  having  the  composition  of  alcohols. 

Sugars  of  the  formula  C6H12O6,  or  the  glucoses,  have  two 
atoms  of  hydrogen  less  than  the  saturated  alcohols,  and 
are  classed  as  aldeJiydes  of  these  alcohols  ;  this  classifica- 
tion is  justified  by  the  fact  that  dextrose,  when  acted  upon 
by  nascent  hydrogen,  is  converted  into  mannite,  just  as 
acetic  aldehyde  is  changed  into  ethylic  alcohol  by  the  same 
agent. 

Sugars  of  the  composition  C12H22On,  such  as  cane-sugar, 
are  so  constituted  that  one  molecule  is  equivalent  to 
two  molecules  of  the  glucoses,  minus  one  molecule  of 
water— as,  C]QH220U  =  (2C6H12O6  -  OH2) ;  these  are  called 
diglucosic  alcohols.  The  carbohydrates  starch,  cellu- 
lose, and  a  few  others,  having  the  formula  C6H1005,  or 


12  CHEMISTRY -OF  THE  SUGARS  AS  A  CLASS. 

multiples  of  it,  may  be  regarded  as  the  oxygen  ethers  or 
anliydrides  of  the  glucoses  or  the  diglucosic  alcohols,  in- 
asmuch as  they  differ  from  them  by  one  molecule  of  water. 
The  most  important  of  the  sugars  may  be  arranged,  ac- 
cording to  their  chemical  relations,  as  follows  : 

I.  SATURATED  ALCOHOLS. 

Triatomic.  Pentatomic.  Hexatomic. 

Dambonite.  (C6H7)v  (OH)5  (C6H8)VI(OH)6 

(C4H6y"(OH)s.  Quercite.  Mannite. 

Derived  from  butylene,  Finite.  Dulcite. 

C4H8.  Derived  from  the  hydro-  Isodulcite. 

carbon  C6H7.  Rhamnegite. 

Derived  from  the  hydro* 
carbon  C6H8. 

II.  ALDEHYDES  OF  THE   HEXATOMIC  ALCOHOLS 

(GLUCOSES). 
C,H,408  — Ha  =C6H1206. 

Dextrose.  Mannitose.  Eucalyn. 

Levulose.  Dulcitose.  Inosite. 

Galactose.  Dambose. 

III.  DIGLUCOSIC    ALCOHOLS. 

[Related  to  the  glucoses  by  C12H22On  =  (2C6HiaO«  —  HaO)]. 

Saccharose.  Melitose. 

Parasaccharose.  Mycose.          ) 

Lactose.  Trehalose.      f 

Melezitose.  Synanthrose. 

Maltose. 

The  above  grouping  is  based  on  the  modern  theories  of 
organic  chemistry,  which  may  be  useful  in  this  application, 
as  they  have  undoubtedly  been  in  many  others.  A  more 
convenient,  and  possibly  an  equally  scientific  classification 
may  be  made,  based  on  the  relations  of  constitutional  ideii- 


CLASSIFICATION.  13 

tity  or  similarity  in  regard  to  their  empirical  formulas,  and 
general  chemical  and  physical  properties.  The  true  sugars 
or  carbohydrates  have  the  characters  pre-eminently  sac- 
charine, while  the  saccharoids  differ  much  from  them  in 
atomic  constitution  and  many  other  properties.  The  car- 
bohydrates are  classed  as  fermentable  and  non-fermen- 
table. Class  I.  is  again  divided  into  A,  Glucoses,  and  B, 
Sucroses,  the  former  being  capable  of  fermenting  directly 
without  previous  conversion  into  any  other  body. 


CHEMISTRY  OF  THE  SUGARS  AS  A  CLASS. 


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FORMATION  IN  PLANTS.  15 

Formation  in  Plants.— Cane-sugar  is  probably  de- 
rived from  the  starch,  existing  in  the  plant,  which  is  con- 
verted by  the  action  of  diastase,  or  a  similar  ferment,  into 
the  soluble  form,  or  dextrin,  and  then  into  sugar  by  the 
fixation  of  the  elements  of  water.  According  to  Payen, 
all  immature  parts  of  the  sugar-cane  contain  starch,  while 
at  maturity  there  is  not  a  trace  of  it. 

M.  A.  Richard,  in  his  Precis  de  Botanique,  gives  the 
following  account  of  the  conversion  of  the  amylaceous 
matter  into  sugar:  "  Starch  has  the  same  chemical  compo- 
sition as  cellulose — carbon  and  the  elements  of  water.  It 
is  found  largely  in  all  the  organs  of  the  plant,  where  it 
accumulates  to  serve  for  nutrition ;  but,  like  cellulose, 
starch  is  insoluble  in  water.  In  order  to  render  it  assimi- 
lable it  must  be  made  soluble,  and  this  is  effected  by  a 
peculiar  body,  diastase,  discovered  by  MM.  Payen  and 
Persoz,  which  exists  or  is  formed  under  certain  circum- 
stances in  all  organs  containing  starch.  Diastase  possesses 
the  peculiar  property  of  converting  starch  into  a  saccha- 
roid  and  soluble  matter,  dextrin,  which  is  dissolved  and 
carried  by  the  juice  to  all  parts  of  the  plant.  Now,  the 
dextrin,  combining  with  one  equivalent  more  of  water,  is 
changed  into  cane-sugar.  The  latter  may  be  modified  in 
its  turn,  combining  with  additional  water  and  producing 
dextrose,  or  grape-sugar." 

As  a  result  of  numerous  experiments  made  by  M.  Biot* 
upon  the  conditions  of  the  formation  and  change  of  sugar 
in  various  plants,  including  the  sycamore,  maple,  birch,  wal- 
nut, and  wheat,  the  following  conclusions  were  arrived  at : 
1.  The  existence,  at  a  certain  age  of  the  plant,  of  grape  of 

*  Compt.  Rend. 


1G  CHEMISTRY  OF  THE  SUGARS  AS  A  CLASS. 

invert  sugar  alone.  2.  The  simultaneous  presence  of  cane 
and  invert,  or  grape-sugar.  3.  The  existence  of  different 
sugars  in  different  organs  of  the  same  plant.  4.  The 
natural  and  normal  transformation  of  different  sugars  into 
each  other,  and  even  into  dextrin.  5.  The  converse  of  the 
above— that  starch  and  dextrin  are  converted  into  cane- 
sugar. 

Berthelot  and  Buigiiet,*  in  experiments  on  the  orange, 
have  shown  the  remarkable  fact  that  cane-sugar  forms  in 
the  presence  of  free  citric  acid,  which  appears  to  be  not 
only  without  invertive  action,  but  actually  prevents  the 
formation  of  invert-sugar. 

C.  T.  Jackson  f  considers,  in  the  case  of  the  sugar  mil- 
let, that  cane  is  derived  from  invert- sugar  at  the  period  of 
maturity.  To  this  leery,  $  from  the  result  of  his  exami- 
nation of  the  growing  sugar-cane,  assents,  but  claims  an 
important  role  for  the  influence  of  light  in  the  transforma- 
tion. 

Synthetical  Studies  of  the  Sugars. — It  has  long 
been  a  favorite  idea  with  chemists  to  produce  the  sugars, 
and  especially  cane-sugar,  by  artificial  means ;  but  up  to 
the  present  there  has  been  but  small  success  in  this  de- 
partment of  research".  Honig  and  Rosenfeld  (Ber.  CJicm. 
Gesell.,  x.  871)  attempted  to  produce  the  alkali 'and  halo- 
gen combinations  of  dextrose.  Pohl§  states  that  sugar 
may  be  produced  from  assamar  (see  page  42)  when  the 
aqueous  solution  is  allowed  to  remain  a  long  time  at  rest. 
Assamar,  according  to  Heichenbach,  has  the  formula 
C24H26O13,  whence 

*  Compt.  Rend.,  li.  1094.  J  Ann.  CJiim.  Pliys.,  [4]  v.  350. 

\Ibid.,  xlvi.  55.  §Jow\Pk.  Chem.,  Ixxxii.  148. 


SACCHARIN—  ROTATORY  POWER.  17 


As  the  nature  of  assamar,  however,  is  entirely  unknown, 
the  equation  has  no  theoretical  value.  Lowig  *  obtained 
a  fermentable  syrup  from  oxalic  ether,  and  Henard  f  has 
found,  among  the  products  of  the  action  of  electrolytic 
oxygen  on  glycerin  and  dilute  sulphuric  acid,  a  body 
CCH12O6  which  reduces  alkaline  solution  of  oxide  of  cop- 
per, and  on  oxidation  gives  oxalic  acid. 

By  the  action  of  alkalies  on  invert  -sugar  Peligot  J  recog- 
nized a  substance  among  the  products  which  he  called  sac- 
charin. This  body  has  the  composition  of  cane-sugar, 
C12PI22On,  and  crystallizes  in  large  right-rhombic  prisms  ; 
the  taste  is  not  sweet  ;  soluble  in  cold  water  ;  not  fermenta- 
ble with  yeast  ;  largely  volatile  ;  does  not  reduce  alkaline 
solution  of  oxide  of  copper  ;  nitric  acid  oxidizes  it  to 
oxalic  acid  ;  specific  rotatory  power  [a]  D  =  93°  5r.§ 

Optical  Rotatory  Power.  —  Aqueous  solutions  of  most 
sugars  have  the  property  of  rotating  the  plane  of  polar- 
ized light  either  to  the  right  or  left.  The  degree  of  rota- 
tion varies  with  different  sugars,  and  with  the  majority  the 
direction  of  the  rotation  is  to  the  right  and  is  uninflu- 
enced to  any  great  extent  by  the  temperature.  Levulose 
rotates  to  the  left,  and  the  temperature  exercises  great  in- 
fluence. A  freshly-prepared  solution  of  crystallized  dex- 
trose, and  some  other  sugars,  possesses  a  rotation  of  double 
the  ordinary,  but  when  it  is  left  to  itself  for  some  hours, 

*  Jour.  Pk.  Chem.,  Ixxxiii.  129.  f  Compt.  Rend.,  Ixxxii.  502. 

\lbid.,  Jxxxix.  918  ;  xc.  1141. 

§  Later  investigations  of  Scheibler  (Neue-Zeits,  v.  261)  lead  him  to  assign  the 
formula  C6Hio05;  see  also  Kolli  and  Vachovic  (Ibid.,  v.  170)  on  the  synthesis 
of  sugars. 


18  CHEMISTRY  OF  THE  SUGARS  AS  A  CLASS. 

or  heated,  the  specific  rotatory  power  is  reduced  to  the 
normal  degree,  where  it  remains  constant.  This  property 
of  sugars  is  called  Birotation  (see  page  79). 

RELATION   OF   SUGARS   TO   THE  PHENOMENA   OF   FERMENTA- 
TION. 

The  ability  to  decompose  under  the  influence  of  a  nitro- 
genous exciting  agent  or  ferment  is  perhaps  the  most  dis- 
tinctive characteristic  of  these  bodies.  By  placing  a  solu- 
tion of  sugar  under  suitable  conditions  the  evolution  of 
carbonic  acid  or  hydrogen,  and  the  formation  of  alcohol 
or  lactic  acid,  is  positive  proof  of  the  presence  of  sugar  or 
saccharoidal  matter.  As  far  as  known  there  are  no  ex- 
ceptions to  this. 

The  sugars  are  capable  of  undergoing  various  kinds  of 
fermentation,  the  difference  consisting  in  the  nature  of  the 
ferment,  the  temperature,  the  concentration  of  the  fluid 
in  which  the  action  takes  place,  and  the  products  formed. 

Mucous  Fermentation  (Gmelin's  Handbook  Cav.  Soc., 
xv.  280). — This  fermentation  takes  place  under  the  influ- 
ence of  a  peculiar  mucous  ferment  which  is  composed  of 
sporules  of  .0012  to  .0014  mm.  in  diameter,  and,  when  in- 
troduced into  cane-sugar  solutions  containing  albumen, 
causes  the  sugar  to  be  resolved  into  mannite,  gum,  and  car- 
bonic acid.  100  pts.  of  cane-sugar  yield,  on  the  average, 

59.01  pts.  mannite, 
45.50    "    gum, 

corresponding  to  the  equation : 

25C12H22On  +  13H20  =  12C12H20010  +  24C6HUO6  +  12CO2 
Under  conditions  not  accurately  known  hydrogen  is  also 


MUCOUS  FERMENTATION  OF  CANE-JUICE.  19 

evolved.  When  a  greater  proportion  of  gum  is  formed 
than  that  given  above,  the  sporules  are  larger  and  are 
probably  a  distinct  ferment  (Pasteur*).  Mucous  fer- 
mentation requires  access  of  air,  and  likewise  the  presence 
of  nitrogenous  matter ;  neither  acid  nor  alcohol  is  pro- 
duced (Hochstetter).  The  fermentation  is  prevented  by 
sulphuric  acid,  hydrochloric  acid,  and  alum.  Fresh  beet- 
juice,  on  exposure  to  the  air,  becomes  gummy,  and  is 
found  to  contain  mannite,  gum,  tartaric  acid,  and  uncrys- 
tallizable  sugar. 

According  to  Plagne,f  the  juice  of  the  sugar-cane  con- 
tains a  white,  non-azotized  substance,  which  becomes 
brown  and  moist  in  contact  with  the  air,  is  soft  and 
difficult  to  dry,  soluble  in  water,  insoluble  in  alcohol  and 
ether,  and  is  precipitated  from  watery  solutions  by  oxide 
of  lead,  mercurous  salts,  and  alcohol.  It  converts  cane- 
sugar  into  a  substance  intermediate  between  starch  and 
gluten,  which  forms  quickly  and  somewhat  abundantly 
in  syrups,  rendering  them  viscid,  ductile,  and  uncrystal- 
lizable.  If,  therefore,  the  juice,  after  being  treated  with 
lime,  is  left  to  stand  forty-eight  hours,  a  jelly  is  produced 
from  wThich  alcohol  throws  down  a  soft  white  precipitate 
which  dries  to  a  nacreous  mass,  dissolving  but  sparingly 
in  hot  and  cold  water,  even  when  moist,  but  swells  up 
again  to  a  transparent  jelly,  which,  treated  with  nitric 
acid,  yields  only  oxalic  acid.  It  is  not  colored  by  iodine 
or  converted  into  glucose  by  acids,  and  does  not  give  off 
ammonia  when  submitted  to  dry  distillation.  ;f 

Lactous  or  Butyrous  Fermentation. — Various  su- 

*Bull.Soc.  Chim,  1861,  30.  \Journ.  Pharm.,  xxvi.  248. 

{See  Phil.  Mag.,  1846,  23  ;  Scheibler  (Zeit.  f.  Rubenz,  xxiv.  309). 


20  CHEMISTRY  OF  THE  SUGARS  AS  A  CLASS. 

gars  and  dextrin,  when  subjected  to  the  action  of  particular 
ferments,  are  converted  into  lactic  acid,  the  change  consist- 
ing in  the  resolution  of  the  molecule,  preceded  in  some 
cases  by  the  assumption  of  the  elements  of  water — as, 

(1)  C6H1206  -  2C3H603. 

Dextrose.          Lactic  acid. 

(2)  Cja.0,,  +  H.O  =  4C.H.O.- 

Lactose.  Lactic  acid. 

The  lactous  fermentation  requires  a  temperature  of  20° 
to  40°  C.,  the  presence  of  water,  and  certain  ferments — viz., 
albuminous  substances  in  a  peculiar  state  of  decompo- 
sition, such  as  caseine,  gluten,  and  animal  membranes. 
The  action  depends  upon  a  ferment  contained  in  or  formed 
by  the  above  substances,  and,  according  to  Blondeau,  is 
the  vegetable  growth  Penicilium  glaucum. 

When  the  lactous  fermentation  is  set  up  in  a  suitable 
solution,  it  is  because  certain  bodies  present  in  the  air  de- 
velop the  ferment  in  the  liquid ;  if  the  air  is  excluded,  or 
only  heated  air  has  access  to  the  solution,  no  lactous  fer- 
mentation will  take  place,  unless  the  proper  ferment  is 
added  (Pasteur  *).  According  to  Bechamp,  ordinary  chalk 
contains  in  itself  a  ferment  recognizable  by  the  microscope  ; 
he  found,  when  artificial  carbonate  of  lime  was  used  for  the 
lactous  fermentation,  that  the  operation  did  not  take  place 
at  all.  The  spontaneously-developed  fermentation  of  sac- 
charine juices  containing  nitrogen  is  sometimes  lactous  and 
sometimes  vinous,  but  more  frequently  both  together. 

In  order  that  a  sugar  solution  may  undergo  the  lactous 
fermentation  there  is  added  to  it,  at  a  temperature  of  from 

*  Ann.  Chim.  Phys.,  52. 


BUTYROUS  FERMENTATION.  21 

20°  to  40°  C.  (best  about  30°),  some  putrid  cheese  or  a  suit- 
able animal  membrane,  and  a  considerable  quantity  of 
chalk  to  neutralize  the  lactic  acid  as  it  is  formed,  because 
the  presence  of  the  latter  hinders  the  progress  of  the  fer- 
mentation by  coagulating  the  caseine  of  the  cheese.  The 
whole  is  left  for  two  or  three  weeks,  when  a  crystalline 
deposit  of  calcium  lactate  is  formed;  if  this  is  not  re- 
moved it  gradually  redissolves,  owing  to  the  ensuing 
butyrous  fermentation  whereby  butyric  acid  is  formed, 
whose  calcium  salt  is  soluble  ;  hydrogen  is  evolved  at  the 
same  time.  The  reaction  is  illustrated  by  the  equation : 

2C3H603   =   C4HS02  +  2C02  +  H2. 

Lactic  acid.          Butyric  acid. 

Pasteur  considers  that  the  butyrous  fermentation  is  ex- 
cited by  a  peculiar  infusoria.  Slightly  alkaline  solutions 
are  best  suited  to  the  development  of  the  lactous  fermenta- 
tion, neutral  liquids  for  the  development  of  yeast  (Pasteur). 
Lactous  fermentation  may  be  replaced  by  a  conversion  of 
the  cane-sugar  into  acetic  acid  instead  of  lactic ;  this 
change  is  said  to  take  place  under  the  influence  of  the 
Torula  aceti  (Blondeau).  According  to  Boutroux  (Compt. 
Rend.,  1878,  No.  9),  the  lactic  ferment,  and  the  fungus 
Mycoderma  aceti  which  is  associated  with  the  acetification 
of  alcohol,  are  identical,  the  function  varying  with  the  com- 
position of  the  putrescent  medium. 

Vinous  Fermentation.— The  clear  juice  of  saccharine 
plants,  or  any  other  solution  of  cane-sugar  containing  a 
suitable  nitrogenous  body,  left  to  itself  in  contact  with  the 
air  at  a  temperature  of  20°  to  24°  C.,  becomes  turbid  after 
a  few  hours  and  gives  off  carbonic  acid,  the  temperature  of 
the  solution  rising  at  the  same  time ;  in  from  48  hours  to 
several  weeks,  according  to  the  temperature  and  the  nature 


22  CHEMISTRY  OF  THE  SUGARS  AS  A  CLASS. 

of  the  nitrogenous  matter  present,  the  whole  of  the  sugar 
is  decomposed.  The  fermentation  may  take  place  at  much 
lower  temperatures  than  that  given,  down  to  0°,  but  the 
action  is  then  rendered  very  slow  (Dubrunfaut).  As  soon 
as  the  evolution  of  carbonic  acid  is  terminated,  a  substance 
previously  suspended  in  the  solution,  is  partly  carried  up- 
wards by  the  adhering  gas-bubbles,  and  partly  falls  to  the 
bottom  of  the  vessel ;  this  insoluble  substance  is  the  yeast. 
The  liquid,  after  the  completion  of  the  operation,  contains, 
in  the  place  of  the  sugar,  alcohol,  glycerin,  and  succinic 
acid  mainly,  together  with  traces  of  several  other  bodies. 
The  formation  of  these  products  may  be  roughly  represented 
by  the  following  equations  : 

C6H1206  =  2C.H.O  +  2C02,     (1) 

Dextrose.  Alcohol. 

and 
49C6H12O6+  30H2O  =  12C4H8O4  +  72C3H803  +  30CO2.     (2) 

Succinic  acid.        Glycerin. 

— (Pasteur.*) 

By  far  the  greatest  portion  of  the  sugar  is  converted  into 
alcohol  and  carbonic  acid,  only  from  four  to  five  per  cent, 
being  transformed  into  other  bodies.  The  yeast  itself  takes 
up  from  one  to  one  and  a  half  per  cent,  of  the  elements  of 
the  sugar  in  the  form  of  cellulose  and  fat.  According  to 
Maumene,f  there  is  produced  in  the  vinous  fermentation 
small  quantities  of  other  alcohols,  as  butylic,  amylic,  and 
others,  but  no  methylic.  The  gum,  extractive,  malic  acid, 
and  dextrin  contained  in  fermenting  liquids  are  not  affected 
(Proust  and  Ventzke  J).  When  a  solution  contains  less  than 

*  Ann.  CMm.  Phys.,  58.  J  Jour.  Pk.  Chemie,  xxv.  81. 

t  Traite. 


VINOUS  FERMENTATION.  23 

four  parts  of  water  to  one  of  sugar,  the  fermentation  takes 
place  imperfectly  or  not  at  all. 

The  exact  rationale  of  the  process  of  fermentation  is  a 
matter  of  some  obscurity,  though  it  is  certain  that  the  pre- 
sence of  albuminoid  nitrogenous  matter  is  essential,  as  well 
as  a  peculiar  ferment ;  both  of  these  are  contained  in  yeast. 
The  ferment  is  a  fungoid  growth,  and  is  specifically  diffe- 
rent for  the  various  classes  of  fermentation.  The  fungus 
SaccTiaromyces  cerevisice  appears  to  be  the  exciting  agent 
for  the  vinous  fermentation,  while  Penic ilium  glaucum  per- 
forms the  same  office  in  the  lactous  fermentation  ;  both  are 
found  in  beer-yeast.  Yeast  produced  in  the  alcoholic  fer- 
mentation is  capable  of  exciting  the  same  change,  under 
suitable  conditions,  in  other  saccharine  solutions,  air  being 
necessary  for  the  beginning  of  the  operation,  but  not  for  its 
continuance. 

Cane-sugar,  previous  to  undergoing  the  vinous  fermenta- 
tion, is  converted  into  a  mixture  of  dextrose  and  levulose,  in 
varying  proportions,  by  the  taking  up  of  one  molecule  of 
water.  This  inversion  is  effected  under  the  influence  of  a 
peculiar  body  contained  in  yeast  or  in  the  kernels  of  fruits, 
and  called  by  Barth  *  invertin,  who  describes  it  as  a  white 
powder,  soluble  in  water,  and  giving  a  precipitate  with 
plumbic  acetate  ;  he  gives  the  mean  composition  as 

Carbon 43.90 

Hydrogen 8.40 

Nitrogen 6.00 

Oxygen 41-47 

Sulphur 63 

See  also  Hoppe-Seyler  (Ber.  CTiem.  Gesell.,  iv.  810),  Gun- 
ning (Ibid.,  v.  821),  and  Donath  (Ibid.,  viii.  795). 

*  Ber.  Chem.  Gesell.  t  1878,  No.  5. 


24  CHEMISTRY  OF  THE  SUGARS  AS  A  CLASS. 

« 

A  solution  thus  wholly  or  partially  inverted  exhibits  a 
levo-rotatory  power  with  polarized  light  before  and  during 
the  progress  of  the  fermentation.  It  is  undecided  whether 
the  inversion  takes  place,  as  with  acids,  according  to  the 
equation  : 

C12IL,On  +  H20  =  CCH1206  +  C6H1206, 

or  that  the  relative  proportion  of  the  glucoses  formed  varies 
from  the  above ;  the  inversion  is  not  due  to  the  presence  of 
succinic  or  any  other  acid. 

According  to  Pasteur,  the  following  represents,  within 
narrow  limits,  the  quantitative  results  of  the  vinous  fermen- 
tation of  cane-sugar : 

100  parts  of  saccharose,  equivalent  to  105.36  parts  inverted 
sugar,  give— 

51.11  parts  ethylic  alcohol. 
48.89     "      carbonic  acid. 
.67     "      succinic  acid. 
3.16     "      glycerin. 

1.00.    "     cellulose,  fat,  and  extractive. 
The  glycerin  and  succinic  acid  are  formed  by  the  yeast,  and 
not  by  any  peculiar  ferment. 

Influence  of  Saline  Matters  on  Fermentation.— 
Ammonium  chloride  precipitates  yeast  from  a  liquid,  while 
potassium  silicate  and  borax  coagulate  it.  Maumene  * 
gives  the  following,  showing  the  action  of  salts  on  the  vi- 
nous fermentation :  one  gramme  of  yeast  was  left  for 
three  days  in  contact  with  a  solution  containing  thirty  to 
forty  grammes  of  salt.  The  results  are  approximate  only— 
1.  Fermentation  more  or  less  aided. — Sulphates  of  po- 
tassium1, sodium14,  magnesium19,  calcium22,  zinc25,  copper26, 

*  Traite,  vol.  i. 


ACTION  OF  SALTS  ON  FERMENTATION.  25 

aluminium24  ;  chlorides  of  potassium1,  calcium20,  stron- 
tium23 ;  phosphates  of  potassium3,  calcium21,  ammonium18, 
sodium15 ;  potassium  formiate8 ;  potassium  tartrate9  and  bi- 
tartrate10  ;  sodium  lactate17. 

2.  Fermentation  more  or  less  retarded.  —  Sulphates  of 
iron15  and  manganese16 ;  sodium  sulphite0 ;  nitrates  of  po- 
tassium2 and  ammonium11 ;  chloride  of  barium14 ;  iodide  of 
potassium4 ;  arseniate5  and  butyrate  of  potassium3 ;  borate 
of  sodium9,  Rochelle  salt9.     (The  figures  refer  to  the  rela- 
tive order  of  activity.) 

3.  Inversion    increased    without  fermentation    being 
affected. — Potassium    nitrite,    chromate,   bichromate;    so- 
dium chloride,  nitrite,  acetate ;  ammonium  chloride ;  mer- 
curic cyanide/" 

Tlie  Cellulosic  Fermentation. — According  to  E.  Du- 
ring cane-sugar  is  capable  of  breaking  up,  under  the  influ- 
ence of  a  peculiar  ferment  and  certain  conditions,  into 
levulose  and  cellulose,  as  shown  by  the  following  equation  : 

C11HH011  =  C.H..O.  +  CCH,50,. 

Cane-sugar.          Cellulose.  Levulose. 

During  the  progress  of  this  fermentation  the  cane-sugar  is 
transformed  into  levulose ;  in  the  simplest  phase  of  the 
operation  no  gas  is  disengaged,  but  if  the  solution  becomes 
acid  carbonic  acid  appears,  though  acetic  acid  is  princi- 
pally formed.  During  the  continuance  of  the  fermenta- 
tion a  quantity  of  white  clots  are  formed,  which,  following 
M.  Durin,  are  pure  cellulose.  These,  on  being  added  to  a 
sugar  solution,  can  excite  in  it  the  same  change  by 

*  Compare  results  of  Knapp,  Ann.  der  CJiemie,  clxiii.  G5  ;  Dubrunfaut,  La 
Sucrerie  Indigene,  xii.;  Dumas,  Mon.  Scientif.,  1872;  Kolbe  and  Meyer,  J.  Pk. 
Ch.,  ix.  133. 

f  La  Sucrerie  Indigene,  xi.  8. 


26  CHEMISTRY  OF  THE  SUGARS  AS  A  CLASS. 

which  they  were  themselves  formed  ;  the  temperature  of  30° 
is  the  most  favorable.  Dextrose  and  mannite  do  not  un- 
dergo this  species  of  fermentation. 

GENERAL    CHEMICAL    PROPERTIES     OF    SUGARS. 

Action  of  Heat. — Some  sugars  containing  water  of 
crystallization — as  dextrose,  melitose,  eucalyn,  inosite,  and 
trehalose — lose  it  at  100°,  melezitose  at  110°,  and  mycose 
at  130°.  At  somewhat  higher  temperatures  the  glucoses 
give  up  a  further  quantity  of  water  and  yield  anhydrides 
analogous  to  mannitan.  Thus, 

Dextrose  C6H12O0  -  H2O  =  C6H]0O5. 

Glucosan. 

As  the  temperature  is  increased  a  number  of  indefinite 
bodies  are  formed,  known  as  caramel  and  its  derivatives. 
Submitted  to  dry  distillation,  the  sugars  are  resolved  into 
carbonic  oxide,  carbonic  acid,  methane,  acetic  acid,  alde- 
hyde, furfurol,  acetone,  liquid  hydrocarbons,  and  a  black 
coal. 

Action  of  Oxidizing  Agents. — The  sugars  are  easily 
oxidized  with  powerful  oxidizing  agents,  yielding  pro- 
ducts of  simpler  composition,  as  carbonic,  formic,  and 
oxalic  acids.  Glucose  and  levulose  reduce  salts  of  copper, 
silver,  mercury,  and  bismuth  quite  readily.  Haberman 
and  Honig  (Cliem.  Centb.,  xiii.  119)  claim  that,  by  the 
action  of  Tiydrated  oxide  of  copper  on  sugar  solutions  in 
the  heat,  (1)  levulose,  dextrose,  invert,  milk,  and  cane- 
sugars  reduce  to  sub-oxide  ;  (2)  the  reaction  is  very. quick 
with  levulose  and  invert-sugar,  but  less  so  with  dextrose, 
while  with  cane-sugar  it  only  begins  after  several  hours' 
boiling,  and  even  then  the  action  is  probably  due  to  in- 
version ;  (3)  the  oxidation  products  are  carbonic,  formic, 


OXIDATION  OF  CANE-SUGAR.  27 

and  glycollic  acids,  together  with  an  amorphous  body. 
By  prolonged  boiling  with  nitric  acid  saccharose  yields 
mostly  oxalic  acid.  At  lower  temperatures  and  with  more 
dilute  acids  products  are  formed  nearer  in  constitution  to 
the  sugars,  as  mucic,  saccharic,  tartaric  acids,  and 
sometimes  racemic.  The  formation  of  the  isomeric  acids 
mucic  and  saccharic  is  illustrated  by  the  equation : 

Tartaric  acid  is  probably  formed  by  the  further  oxidation 
of  saccharic  acid,  racemic  by  the  oxidation  of  mucic. 
Saccharose  and  dextrose,  and  most  other  sugars  yield  by 
this  gradual  oxidation  only  saccharic  acid ;  lactose  yields 
mucic  acid  principally,  with  a  small  quantity  of  saccha- 
ric ;  melitose  gives  saccharic  mainly,  with  a  small  quantity 
of  mucic  acid. 

The  following  table  of  Horneman*  shows  the  relative 
quantities  of  tartaric  and  racemic  acids  formed  by  the 
oxidation  of  various  carbohydrates : 


ioo  parts  will  give 

Pa 
Tartar  ic. 

rts  of 
Racemic. 

CC    A 

44  6 

Guru     ........ 

5-5  o 

07  o 

CQ  7 

4O  "3 

IOO  O 

IOO.O 

Levulose     

IOO  O 

72.6 

27.4 

Mucic         "     

? 

IOO.O 

Under  the  influence  of  chlorine  and  bromine  some  sugars 
yield  two  acids  containing  six  atoms  of  carbon — isodi- 
glycoethylenic  acid  C6H1206,  and  gluconic  acid  C6H12O7. 


*  Jour.  Prak.  CJiemie,  Ixxxix.  283. 


2$  CHEMISTRY  OF  THE  SUGARS  AS  A  CLASS. 

The  first  is  formed  when  a  solution  of  bromine  is  made 
to  act  on  milk-sugar ;  the  second  when  a  current  of 
chlorine  is  passed  through  a  dilute  solution  of  cane-sugar 
or  dextrose.  Levulose  and  sorbite  break  up  by  the  action 
of  chlorine  into  glycollic  acid. 

Reactions  with  Acids. — Sugars  form  with  acids  com- 
pounds analogous  to  ethers,  acting  like  polyatomic  alco- 
hols. Concentrated  nitric  acid,  or  a  mixture  of  nitric 
and  sulphuric  acids,  acts  upon  saccharine  bodies,  giving 
rise  to  nitro- substitution  compounds  in  which  the  univa- 
lent  radical  NO2  takes  the  place  of  an  atom  of  hydrogen. 
Thus,  in  the  case  of  saccharose,  the  product  has  the  com- 
position C12H18(NO2)4On.  With  inosite,  liex-nitro  inosite  is 
produced,  C6H6(NO3)"O6.  Isodulcite,  dextrose,  milk-sugar, 
and  trehalose  yield  nitro  compounds  whose  composition  is 
not  exactly  known. 

Sulphuric  acid  acts  on  cane-sugar  much  more  strongly 
than  upon  the  glucoses.  A  strong  syrup  of  cane  or  milk- 
sugar  mixed  with  concentrated  sulphuric  acid  is  immedi- 
ately decomposed  with  strong  intumescence,  attended  with 
an  evolution  of  sulphurous  acid  gas  and  various  volatile 
compounds,  a  black  carbonaceous  residue  being  left. 
Dextrose,  under  the  same  circumstances,  gives  without 
blackening,  a  sulpho-acid  C24H48SO27  =  4CCH12O6.SOS,  the 
reaction  being  precisely  similar  to  that  of  organic  acids 
with  sugar.  Phosphoric  acid  appears  to  act  in  the  same 
manner. 

Saccharides. — The  organic  acids  yield,  with  sugars, 
ethereal  compounds  called  saccharides.  Berthelot*  has 
produced  this  class  of  compounds  by  heating  dextrose 
with  various  organic  acids,  such  as  acetic,  butyric,  stearic, 

*Ann.  CMm.  Phys.,  liv.  78. 


ACTION  OF  ACIDS  AND  ALKALIES.  29 

but  has  found,  as  a  general  rule,  that  the  number  of 
molecules  of  water  eliminated  is  one  in  excess  of  the 
number  of  molecules  of  the  monobasic  acid  taking  part  in 
the  reaction.  So  that  the  products  obtained  are  ethers  of 
glucosan,  and  not  of  glucose,  as  below : 

(1)  C6H1206  +  2C4H802  =  CCH10(C4H70)U  +  2H2O. 

Dextrose.      Butyric  acid.         Dibutyric  glucose. 

(2)  C6H,,0,  +  20,11,0,  =  C6H,(C4H,0)505  +  3H,O. 

Dibutyric  glucosan. 

By  the  action  of  tartaric  acid  on  saccharose,  dextrose, 
and  lactose,  according  to  the  same  chemist,  entirely  simi- 
lar derived  -compounds  are  formed,  which  bear  the  rela- 
tion to  glucosan  shown  in  the  equation  (2).  Mannite  also 
gives  compounds  likewise  related  to  mannitan. 

Action  of  Weak  Acids— Inversion.— When  cane- 
sugar  is  heated  with  dilute  sulphuric  acid  or  hydrochloric 
it  is  converted  into  dextrose  and  leviilose  : 

C12H22On  +  H20  =  C6H1206  +  C6HI206. 

Melezitose  yields  two  molecules  of  dextrose  ;  melitose,  one 
molecule  of  dextrose  and  one  of  eucalyn ;  and  lactose, 
two  molecules  of  galactose  (Pasteur). 

Action  of  Alkalies. — Dextrose  is  much  more  easily 
acted  upon  by  caustic  alkalies  than  saccharose.  The  de- 
composition of  aqueous  solutions  of  the  glucoses  takes 
place  slowly  in  the  cold,  more  quickly  on  heating,  the 
liquid  first  turning  yellow  and  then  brown,  yielding 
humus-like  bodies.  Dextrose  thus  treated  gives  glucic 
acid  as  the  first  product  of  the  reaction.  The  sucroses 
C12H22On  are  not  attacked  by  dilute  alkalies  in  the  cold, 
and  but  slowly  on  heating ;  they  are  decomposed  by  boiling 


30  CHEMISTRY  OF  THE  SUGARS  AS  A  CLASS. 

with  concentrated  alkaline  solutions.  When  fused  with 
caustic  alkalies  they  yield  oxalic  acid. 

Ammonia,  in  the  form  of  gas  or  in  aqueous  solution, 
when  allowed  to  act  on  the  sugars  and  some  other  carbo- 
hydrates, is  capable  of  forming  compounds  with  them 
somewhat  resembling  gelatin,  and  containing  in  some 
cases  from  14  to  19  per  cent,  of  nitrogen.  Dusart,  by 
heating  dextrose,  lactose,  and  starch  with  aqueous  ammo- 
nia in  sealed  tubes  to  150°  C.,  obtained  nitrogenous  sub- 
stances which  were  precipitated  by  alcohol  in  tenacious 
threads,  forming  with  tannic  acid  an  insoluble,  non-putre- 
fying compound.  As  it  has  been  observed  that  bone  gela- 
tin approximates  in  composition  to  an  amide  of  the 
carbohydrates,  the  above  facts  are  of  considerable  inte- 
rest. 

C.H.,0.  +  2NH3  =  C6H10NA  +  4HaO. 

Gelatin. 

It  has  also  been  observed  that  gelatin,  when  boiled  with 
sulphuric  acid,  yields,  among  other  products,  sugars  re- 
sembling the  glucoses. 


CHAPTER  II. 


CANE-SUGAR  OR  SACCHAROSE   C12H220U. 

Common   Sugar — Crystallizable    Sugar — Sucrose — Sucre 
de  Canne,  Fr. — JRoTirzucJcer,  Gr. 

Occurrence. — Cane-sugar  is  widely  diffused  in  the 
vegetable  kingdom,  being  found  more  generally,  and  in 
greater  quantities  among  the  grasses.  The  sugar-cane, 
SaccJiarum  officinarum,  contains  often  more  than  twenty 
per  cent,  of  sugar,  unmixed,  it  is  claimed,  with  any  other 
sugar,  when  the  plant  is  perfectly  ripe.  The  following 
analyses  of  the  cane  are  by  O.  Popp  * : 


From  Martinique  and 
Guadaloupe. 

From  Cairo. 

From 
Upper  Egypt. 

Water                  

7°  22 

72  T^ 

72  I  ^ 

Cane-susrar  

17  80 

16  oo 

18  10 

.28 

2  3O 

2C 

Cellulose 

Qon 

Q  2O 

Q  IO 

Salts                    

4.O 

qe 

42 

IOO.OO 

IOO.OO 

100.00 

The  stems  of  SorgTium  saccliaratum  and  8.  Holcus, 
when  quite  ripe,  contain  9  per  cent,  cane-sugar  unmixed 
with  fruit-sugar  (Goessman) ;  the  unripe  stems  carry  only 
starch  and  grape-sugar.  P.  Collier  f  has  found  in  the 

*  Zeit.  fur  Chemie,  1870,  328. 

f  Report  to  the  Commissioner  of  Agriculture,  1879,  and  Aug.  1,  1880. 
Washington,  U.S.A. 

81 


32  CANE-SUGAR  OR  SACCHAROSE. 

juice  of  different  varieties  of  sorghum  from  15.95  per  cent, 
cane  and  .65  per  cent,  of  grape-sugar,  to  13.90  per  cent, 
cane  and  1.45  per  cent,  grape-sugar,  when  the  canes  are 
quite  ripe.  The  juice  from  the  stems  of  Indian  corn  or 
maize  (Zea  mays),  according  to  the  same  authority,  con- 
tained 12.09  per  cent,  cane-sugar  and  .68  per  cent,  grape- 
sugar.  The  nectar  of  flowers  contains  in  vert- sugar  with  a 
considerable  proportion  of  cane-sugar,  the  latter  amount- 
ing in  the  case  of  the  fuchsia  to  three  or  four  times  the 
quantity  of  fruit-sugar  (A.  S.  Wilson,  Cliem.  News, 
xxxviii.  93). 

Many  fleshy  roots  carry  considerable  quantities  of 
cane-sugar,  notably  those  of  Angelica  arcliangelica,  Beta 
vulgaris,  Cheer opliyllum  bulbosum,  CMcorium  intybus, 
Daucus  carota,  Hellantlius  tuberosus,  Leontodon  tarax- 
acum, and  others.  The  common  beet  (Beta  vulgar  is) 
averages  from  seven  to  eleven  per  cent,  of  cane-sugar, 
though  in  particular  cases,  owing  to  high  cultivation,  the 
amount  has  reached  fourteen  per  cent.*  The  beet  contains 
no  other  sugar  besides  saccharose.  According  to  W. 
Stein, f  eight  per  cent,  of  sugar  is  obtainable  from  the  mad- 
der-root, though  it  contains  fourteen  jjer  cent.,  partly  un- 
crystallizable. 

Cane-sugar  occurs  in  the  stems  and  trunks  of  trees, 
as  the  sugar-maple,  Acer  saccJiarinum,  the  sycamore, 
some  species  of  Betula,  in  the  vernal  juice  of  Juglans 
alba,  Tilia  Europcea,  and  in  several  palms,  especially 
Saguerus  Rumpliii,  or  the  sago  palm,  and  the  Cocos  nuci- 
fera,  or  oocoanut-tree.  The  leaves  of  many  plants  con- 
tain sugar.  A.  Petit  found  in  vine-leaves  .92  per  cent,  of 

*  Payen,  Compt.  Rend,,  xl.  769  ;  Schmidt,  Ann.  der  Chemie,  Ixxxiii.  325. 
f  Journ.  fur  Prak.  Chemie,  cvii.  444. 


SUGAR  IN  FRUITS.  33 

cane  and  2.62  per  cent,  of  grape  sugar,  and  also  the  same 
bodies  in  cherry-leaves. 

The  sugar  of  fruits  at  the  season  of  maturity  is  always 
cane-sugar,  but  by  the  influence  of  a  peculiar  ferment  it 
may  be  partially  or  wholly  converted  into  a  mixture  of 
dextrose  and  levulose,  which  is  commonly  called  fruit- 
sugar.  Ripe  fruits  thus  sometimes  contain  only  fruit- 
sugar,  and  at  others  a  mixture  of  cane  and  fruit  sugars. 
Buignet  *  gives  in  the  following  table  the  saccharine 
content  of  most  of  the  common  fruits,  with  the  amount 
of  acid  present : 


Cane-Sugar. 

Fruit—  Sugar. 

Acid. 

6  04. 

2  74 

I  864 

Pineapples     .         

ii  11 

I  08 

C.A  7 

oo 

IO  OO 

66  1 

Lemons 

41 

I  06   • 

4706 

FigS                     

oo 

II  5^ 

oc,7 

6  11 

4.08 

CCQ 

2.OI 

5.22 

1.380 

Gooseberries   

OO 

6  40 

I  c,74 

4.22 

4.36 

.448 

.02 

1.07 

I.QOO 

Pears  (\lacleleine)  ...       

16 

8.42 

.lie 

5  28 

8.72 

1.148 

it 

2  IQ 

e  AC 

611 

Prunes                                        

^  24 

1.41 

1.288     . 

Grapes  (hothouse)  

.OO 

17.26 

•  345 

.OO 

1.  60 

2.485 

The  formation  of  cane-sugar  in  fruits  is  not  prevented 
by  the  presence  of  acids  (Buignet,  loc.  tit.)  Cane-sugar  is 
also  found  in  melons  and  dates.  Walnuts,  hazel-nuts, 
bitter  and  sweet  almonds  contain  only  cane-sugar  (Pe- 
louze  •)?),  while  the  saccharine  matter  of  others  is  a  mixture 
of  cane  and  fruit  sugar.  The  sugar  of  common  honey  is 
levo-rotatory,  and  is  composed  of  fruit-sugar,  dextrose, 


Ann.  Chim.  Phys.,  [3]  Ixi.  233. 


f  Compt.  Rend.,  xl.  608. 


34  CANE-SUGAR  OR  SACCHAROSE. 

and  cane-sugar.  The  latter  is  found  chiefly  in  the  honey 
of  the  cells,  and  rapidly  disappears  on  keeping,  owing  to 
an  accompanying  ferment.  Cane-sugar  is  not  found  in 
healthy  cereals  and  barley-malt  ready  formed,  but  is  pro- 
duced by  the  action  of  diastase  and  water  in  the  crushed 
grain  (Mitscherlich,  Peligot,  and  Stein).  The  analysis  of 
the  manna  from  Sinai  (from  Tamarix  manniferd)  shows, 
according  to  Berthelot :  * 

55  per  cent,  cane-sugar, 

25  invert-sugar, 

20          "  dextrin. 
And  that  from  Kurdistan : 

61     per  cent,  cane-sugar, 

16.5  invert-sugar, 

22.5       "  dextrin. 

Preparation  from  Natural  Sources. — For  working 
on  the  small  scale  Marggraf  recommends  that  the  plant,  re- 
duced to  as  fine  a  state  of  division  as  is  practicable,  be 
treated  with  strong  boiling  alcohol,  and  the  solution  ob- 
tained filtered  and  allowed  to  cool,  when  the  sugar  crystal- 
lizes out.  To  obtain  cane-sugar  from  fruits  containing  also 
uncrystallizable  sugar, 'Peligot  and  Buignet  \  have  adopt- 
ed the  following  method :  Add  to  the  juice  an  equal 
volume  of  alcohol  to  prevent  alteration,  if  it  is  to  be  kept 
any  length  of  time  before  operating,  and  filter ;  saturate 
the  filtrate  wTth  excess  of  milk  of  lime,  and  again  filter. 
Boil  the  second  filtrate,  when  a  compound  of  cane-sugar 
and  lime  separates,  which  contains  two-thirds  of  the  total 
cane-sugar  present.  Filter,  wash  the  precipitate  well  with 
water,  diffuse  it  in  water,  and  decompose  with  a  stream  of 

*  Compt.  Rend.,  liii.  583.  t  Ann.  Chim.  Phys.,  Ixi.  233. 


CRYSTALLIZATION  OF  SUGAR. 


35 


carbonic-acid  gas.  The  solution  filtered  from  the  car- 
bonate of  lime  is  concentrated  by  heat  (best  in  a  vacuum) 
to  a  syrupy  consistency,  decolorized  by  bone-black,  and 
mixed  with  strong  alcohol  until  it  becomes  cloudy,  when 
it  is  set  aside  to  crystallize.  If  the  solution,  after  treat- 
ment with  carbonic  acid,  yields  a  turbid  filtrate,  solution 
of  basic  acetate  of  lead  is  added,  the  liquid  refiltered,  and 
the  excess  of  lead  removed  from  the  second  filtrate  with 
sulph-hydric  acid  gas. 

Physical  Properties.— Cane-sugar  when  obtained  by 
slow  evaporation  forms  large,  transparent  crystals,  but 
when  the  crystallization  takes  place  rapidly  they  are  much 
modified  and  striated.  When  a  strong  syrup  is  concen- 
trated to  the  proper  consistency,  it  sets,  on  cooling,  to 
a  solid  mass  of  fine  Crystals,  which,  after  being  washed 
with  a  pure  syrup,  constitutes  the  loo/-sugar  of  commerce. 
Sugar  crystallizes  in  the  monoclinic  system,  the  forms  gene- 
rally having  hemihedral  faces,  but  are  often  tabular. 

Fig.  I.  Fig. 


Figs.  1  and  2  show  the  crystallization  of  cane-sugar. 
Axes:  a:  t>  :  c  =  .7952:1:. 70. 

Angle  of  axes  b  and  c  =  76°  44'. 
Angles  pJi'  =  103°  30'. 

m  m  (on  the  side)         =  101°  32'. 
e'e'  (above  p)  =99°. 

a'Ti'  =  64°  30'. 


CANE-SUGAR  OR  SACCHAROSE. 


(See  Wolff,  Jour.  PJc.  CJiemie,  xxviii.  129). 

Ordinary  forms,  m,  p,  li ',  a',  e',  <rZ'2/.  Harder  than  any 
other  sugar  except  lactose.  Fig.  3  represents  fine  crystals 
of  cane-sugar  under  a  moderate  magnifying  power. 


Fig.3. 


Cane-sugar  exhibits  phosphorescence  when  broken,  or 
when  a  strong  electric  discharge  is  passed  through  it. 

SPECIFIC  GEAVITY.  —  1.593  (Joule  and  Playfair),  1.595 
(Maumene),  1.630  (Dubrunfaut),  1.580  (Kopp)  ;  the  latter 
number,  according  to  Gerlach,*  who  has  carefully  experi- 
mented in  this  direction,  is  the  most  correct  —  1.58046 


*  Zeit.  f.  Rubenz.,  xiii.  288. 


SPECIFIC  ROTATORY  POWER. 


37 


C.  being  the  figure  he  obtained  :  melted  barley-sugar  1.509 
(Biot). 

SPECIFIC  ROTATORY  POWER.— This  constant  as  given  by 
different  authorities  for  the  line  D  is  : 


c. 

MD. 

Arndtsen  

77  "3Q4. 

67  02° 

Ann  Chini  Phys  \*\\  54  403 

47  276 

67.  11° 

Stefan               ....       .    . 

q-7  762 

66  ^7° 

Wiener  Ak&d    52    ii    486 

21  608 

66.7^° 

Wild  

30  276 

66.42° 

PoJciristroboni    1865 

Tuchschmid 

27  ddl 

66  48° 

J  Pk  Ghent   [2]    ii    235 

Calderon 

IQ  Q7I 

167  08° 

Cotnpt  Rend    83    303 

Q  q86 

67.I20 

Girard  and  Luynes 

16  *^o 

67    ^1° 

Cotnpt  Rend    80    1354 

Weiss   ...                 .... 

14.  ^70 

66  04.° 

Wiener  A  knd    60    iii    162 

Oudemans  

K   877 

66.00° 

Peg***  Ann.    148    350. 

c  =  No.  of  grammes  of  material  in  100  c.  c.  of  solution. 
The  discrepancies  shown  above  are  principally  due  to  the 
different  conditions  as  to-  concentration  and  temperature 
for  the  various  series  of  experiments.  Schmitz  *  gives  a 
general  formula  when  c  =  85.68  to  10.40  : 

.  [a]  D  =  66.453  —  .  00123621  c  —  .0001 17037c2; 
and  for  more  dilute  solutions  : 

[a]  D  =  66.639  —  .0208195c  +  .00034603c2. 

According  to  Tollens,  f  when  c  =  0  to  18,  and  c  =  18  to  69, 
the  formulas  are  respectively  : 

[a]  D  =  66.8102  —  .()15553c  —  .00005246c2. 
[a]  D  =  66.386    +  .015035c  —  .0003986e<2. 

The  deviation  of  the  D  ray  for  1  mm.  quartz  is  21.67° 
(Broch). 
For  the  transition  tint  (the  mean  yellow  ray)  the  figure 


*  Ser.  Cliem.  GeselL,  1877,1414. 


f  Ibid.,  x.  403. 


38  CANE-SUGAR  OR  SACCHAROSE. 

\a\  ]  =  73.8°  is  the  one  generally  given,  and  which  cor- 
rectly corresponds  to  the  normal  weights  of  the  various 
saccharimeters  using  the .  transition  tint  (within  narrow 
limits).  The  numerical  relation  of  the  rotations  for  the 
line  D  and  the  transition  tint  is  variously  given  at — 

[a]  j  =  1.13061  [a]  D  for  quartz  (Broch),  and 
[a]  j  =  1.129  [a]  D  (Montgolfier  *), 

1.0961, 

'1.034  (Weiss,  Wiener  Akad.,  Ixix.  157), 

for  sugar  solutions. 

Tollens  (Ber.  CJiem.  Gesell.,  13,  19,  2297)  gives  the  rota- 
tory power  of  cane-sugar  in  various  solvents  as  follows  : 

10  per  cent,  solutions. 
[a]D  =  water,  66.667°. 

"  +  ethylic  alcohol,  66.827°. 
"  +  methylic  "  66.628°. 
"  +  acetone,  67.396°. 

The  temperature  exercises  no  important  influence  on  the 
rotatory  'power  (see  page  170). 

Sugar  is  unalterable  in  the  air.     Specific  heat,  .301. 

Action  of  Light.— Raoult  (Journ.  Fab.  Sucr.,  1871) 
states  that  cane-sugar  in  solution  enclosed  in  a  sealed 
tube  from  which  the  air  has  been  expelled  by  boiling,  and 
kept  for  five  months  exposed  to  light,  was  found  to  have 
been  half  converted  into  glucose  ;  a  similar  arrangement  in 
the  dark  remained  unaltered.  Kreuslerf  asserts  that  if 
the  air  and  germs  are  completely  excluded  in  the  above  ex- 
periment no  change  takes  place.  This  view  is  confirmed  by 
Pellet  $  and  Motteu  (Ber.Belg.  Akad.,  1877). 

*  Bull.  Soc.  Chim.,  xxii.  489.  \  Jour.  Fair.  Sucre,  19,  5. 

t  Zeit.  f.  Anal.  Chem.,  xiv.  197. 


SOLUBILITIES. 


39 


Composition. — Cane-sugar  is  composed  of  carbon,  hy- 
drogen, and  oxygen : 


Equivalents. 

Centesimally. 

Carbon     

144. 

42  1  1 

Hydrogen  

22 

6.4T 

Oxygen 

176 

e  T  A  6 

342 

100.00 

Cane-sugar,  whether  obtained  from  the  cane,  beet,  or  any 
other  source,  is  identical  in  every  physical  and  chemical 
property,  and  in  constitution. 

Endosmose.  —  The  endosmotic  equivalent,  according  to 
Joly,  is  7.25,  but  is  not  constant,  depending  on  the  quality 
of  the  membrane,  though  independent  of  the  temperature 
(Schmidt,  Pogg.  Ann.,  102).  It  is  proportional  to  the  den- 
sity of  the  solution. 

Solubilities.  —  Sugar  is  very  soluble  in  water,  the  con- 
centrated solutions  having  that  peculiar  consistency  deno- 
minated syrupy. 

H.  Courtonne,*  confirming  the  results  of  Berthelot  and 
Scheibler,  gives  the  solubility  of  saccharose  at  12.5°  C.  and 
45°  C.  : 


°.     100  grms.  of  water  dissolve  198.647  grms.  sugar. 
45°.       100      "•  "  "         245.000  " 

The  saturated  solution  at 


°  containing  66.5  per  cent. 
45°  "          71.0         " 

The  specific  gravity  of  a  sugar  solution  saturated  at 


*  Zeit.f.  Rubenz.,  1877,  1033. 


40  CANE-SUGAR  OR  SACCHAROSE. 

l?i°  is  1.3272  to  1.330  (Anthon*);  1.345082  (Michel  and 
Kraft  f). 

Brix^:  gives  the  following  formula  for  calculating  the 
amount  of  contraction  produced  by  the  solution  of  cane- 
sugar  in  water : 

V  =  .0288747X  -  .000083613X2  -  .000002051X3, 

wherein  X  —  the  percentage  of  sugar  dissolved ;  at  the 
maximum,  for  a  solution  of  56.25  per  cent.  X  is  equal  to 
.9946. 

Cane-sugar  is  insoluble  in  ether  and  cold  absolute  alco- 
hol ;  eighty  parts  of  hot  absolute  alcohol  take  up  one 
part  of  sugar,  which  it  deposits  on  cooling. §  Aqueous 
alcohol  dissolves  it  more  readily.  Scheibler||  has  calcu- 
lated the  following  table  from  his  experimental  data  on 
the  solubility  of  cane-sugar  in  dilute  alcohol  of  various 
strengths : 


*  Zeit.  f.  Rubenzuclter  Ind.,  1868,  015. 

For  full  tables  of  solubilities  at  different  temperatures  and  densities,  see 

116  and  the  end  of  the  volume, 
f  Ann.  Chem.  Pharm.,  lii.  195. 
t  Zeit.f.  Rubenzucker  Ind.,  1854,  304;  1874,  1111. 
§  Ibid. ,  xxii.  246.  |  Ber.  Chem.  GeselL,  v.  343. 


SOLUBILITY  IN  ALCOHOL. 


Per  cent. 

absolute 

At  o 

0  C. 

At  14 

°  c. 

At  4c 

)°    C. 

alcohol. 

By  volume 

Sp.  Gr  at 

I7^°c. 

Grammes 
in  loo  c.  c. 

Sp.  Gr.  at 

17  y*°  c. 

Grammes 
in  too  c.  c. 

Sp.  Gr.  at 
»7H»C. 

Grammes 
in  TOO  c.  c. 

O 

.3248 

85-8 

.3258 

87-5 

IO5.2 

IO 

.2991 

80.7 

.3000 

81.5 

95-2 

20 

.2360 

74.2 

.2662 

74-5 

9O.O 

30 

.2293 

65-5 

.2327 

67.9 

82.2 

40 

.1823 

56.7 

.1848 

58.0 

74-9 

50 

.1294 

45-9 

•  1305 

47.1 

63.4 

60 

.0500 

32.9 

.0582 

33-9 

49-9 

70 

.9721 

18.2 

.9746 

18.8 

31-4 

80 

.8931 

6.4 

.8953 

6.6 

13-3 

90 

.8369 

•7 

.8376 

.90 

2.3 

97-4 

.8062 

.08 

.8082 

.36 

•  5 

On  comparing  this  table  with  the  one  showing  the  solu- 
bility of  cane-sugar  in  water  (page  116),  it  will  be  seen 
that  the  water  in  mixtures  of  alcohol  and  water  poor  in 
alcohol,  dissolves  more  sugar  than  it  can  per  se ;  but  for 
mixtures  rich  in  alcohol  the  contrary  is  the  case. 

Sugar  has  a  great  tendency  to  form  supersaturated  solu- 
tions, especially  when  the  temperature  has  been  lowered. 
Contact  with  a  solid  body  in  a  fine  state  of  division  at 
once  determines  a  precipitation  of  the  excess  of  sugar 
(Sostman,  Zeit.  f.Riibenz.,  xxii.  837). 

Action  of  Heat. — Pure  cane-sugar  heated  to  100°  C., 
even  for  a  long  time,  is  scarcely  altered  in  the  absence  of 
watery  vapor ;  in  the  presence  of  water  a  relatively  con- 
siderable change  takes  place  (Motteu).  At  173°  to  177°  C. 
it  melts  without  loss  of  weight  to  a  clear  liquid,  which  on 
cooling  solidifies  to  an  amorphous  mass  called  'barley- 
sugar,  gradually  becoming  opaque  and  somewhat  crystal- 
line. If  the  fused  mass  is  kept  at  this  temperature  for  a 
long  time  it  is  altered,  without  loss  of  weight,  into  levolu- 
san  and  dextrose,  as : 


42  CANE-SUGAR  OR  SACCHAROSE. 


Barley-sugar  reduces  less  of  copper  oxide  in  the  alkaline 
solution  of  tartrate  of  copper  than  does  dextrose  ;  sp.  ro- 
tatory power,*  48°. 

Cane-sugar  heated  above  180°  degrees  becomes  brown, 
loses  weight,  and  on  cooling,  if  exposed  to  the  air,  ab- 
sorbs more  water  than  it  lost,  deliquesces,  and  behaves 
with  alkalies  like  dextrose  (Peligot).  When  heated  for  a 
long  time  from  210°  to  220°  it  froths  up,  the  brown  color 
becomes  darker,  and  a  large  quantity  of  water  is  given  off 
containing  traces  of  acetic  acid  and  furf  urol  ;  when  froth- 
ing has  ceased  the  residue  left  is  caramel  mixed  with  some 
unaltered  sugar  and  a  bitter  substance  called  assamar.\ 
When  the  temperature  is  raised,  more  water  is  evolved, 
and  an  insoluble  matter  produced,  which  increases  in 
quantity  when  the  temperature  is  carried  to  250°  to  300°. 
This  insoluble  body  is  of  complex  composition,  being  com- 
posed of  at  least  three  distinct  substances,  caramelene, 
caramelane,  and  caramelin.  According  to  Peligot,  £  on 
heating  cane  or  grape  sugar  to  220°,  and  treating  the  resi- 
due obtained  with  alcohol,  unaltered  sugar  and  a  bitter 
substance  are  dissolved  out,  and  caramel  remains  behind, 
containing  on  the  average,  when  dried  at  180°,  C12H18O9,  or 
two  molecules  less  of  water  than  cane-sugar.  It  is  soluble 
in  water,  precipitated  by  baryta-water  and  subacetate  of 
lead,  not  fermentable,  and  insoluble  in  alcohol. 

When  sugar  is  subjected  to  dry  distillation,  carameliza- 
tion  takes  place  with  evolution  of  gases.  The  gas  given 
off  at  first  is  nearly  pure  carbonic  oxide,  and  afterward 

*  Tollens,  Ber.  Ch.  Gesell.,  x.  1403.  ^  Ann.  Chim.  PJiys.,  Ixxvii.  154. 

\  J.  Pk.  Chem.,  Ixxxii.  148. 


INVERSION. 


43 


carbonic  acid  and  marsh-gas  make  their  appearance.  An 
aqueous  distillate  forms,  which  holds  a  viscid  oil  and  tar, 
besides  acetic  acid,  acetone,  and  aldehyde.  A  voluminous, 
porous  coal  remains,  constituting  32  to  34  per  cent,  of  the 
sugar  treated. 

Inversion  by  Heat. — Water  acts  precisely  as  do  dilute 
acids  in  converting  cane  into  invert-sugar. 

C12H22On  +  H20  =  C6H1206  +  C6H1206 

Dextrose.         Levulose. 

According  to  Gay  on,  *  sugar  solutions  in  sealed  tubes  in- 
vert in  the  cold,  but  much  more  rapidly  when  heated. 
See  also  Heintz  (Zeit.  f.  Rubenz.,  xxiv.  232),  Berthelot 
(Ann.  Cliim.  PTiys.,  Ixxxiii.  106),  and  Pillitz  (Fres.  ZeiL, 
x.  456).  A  series  of  experiments  made  by  Pellet  f  shows 
the  effect  of  concentration  and  temperature  in  causing 
inversion.  The  table  below  gives  the  amount  of  invert- 
sugar  formed  during  ninety-six  hours'  heating : 


Sugar  in  TOO  c.  c. 

At  25°  C. 

At   50°   C. 

At   75°  C. 

10  grm. 

.5975  grm. 

3.0216  grm. 

8.  8100  grm. 

30      " 

.5275 

2.9200.    " 

7-1825     " 

60      " 

.1025     " 

.6450     ' 

5-490       " 

90      " 

Trace. 

.1500     ' 

Maumene,t  as  the  result  of  experiments,  which  are  sup- 
ported by  previously-made  observations  of  Soubeiran, 
Buignet,  and  others,  claims  that  invert-sugar  is  a  sub- 
stance of  variable  composition,  the  latter  depending  upon 
the  facts  as  to  whether  the  inversion  takes  place  under  the 
influence  of  heat  or  acids,  the  time,  degree  of  heat,  rela- 


*  Compt.  Rend.,  1877,  No.  10.  f  Journ.  Fabr.  Sucre,  xix.  10. 

If.  Traite  de  la  Fabrication  du  Sucre,  tome  i.  118-137. 


44  CANE-SUGAR  OR  SACCHAROSE. 

tive  quantities  of  acid  and  sugar,  and  other  circumstances  ; 
that  it  may,  according  to  the  above  conditions,  consist  of 
dextrose,  levulose,  and  an  optically  inactive  sugar  (isome- 
ric  with  the  two  others)  in  all  proportions  ;  and  that  the 
mixture  may  show  the  most  varying  optical  rotation.  A 
solution  of  cane-sugar,  according  to  Maumene,  on  being 
submitted  to  progressively -increasing  inversion,  begins  to 
lose  its  dextro -rotation,  which  is  reduced  to  zero,  after 
which  a  left  rotation  begins  to  appear,  caused  by  the  ex- 
cess of  levulose,  which  attains  a  maximum  ;  the  rotation 
then  gradually  decreases  until  zero  is  again  reached,  and 
then  a  plus  or  minus  reading  is  shown ;  and  finally  there 
is  a  tendency  to  assume  a  permanent  dextro-rotation. 
As  bearing  on  the  estimation  of  cane-sugar  by  Clerget's 
process,  Maumene  allows  that  if  strict  attention  is  paid  to 
the  conditions  laid  down  for  the  method  (seepage  136),  the 
rotation  of  the  inverted  solution  is  constant,  and  hence  no 
error  from  this  source  will  be  introduced. 

Bechamp  *  attributed  the  inversion  that  cane-sugar  un- 
dergoes in  the  presence  of  water  to  the  influence  of  mould 
or  fungi ;  but  the  later  experiments  of  Clasen  f  seem  to  dis- 
prove this.  The  latter  shows  that  water,  acting  as  an  acid, 
hydrates  the  cane-sugar,  air  being  an  important  factor  in 
the  change.  Mcol,f  also,  has  proven  that  sugar  is  quickly 
and  perfectly  inverted  when  heated  in  sealed  tubes  to  130°- 
135°.  A  solution  of  sugar  may  be  preserved  for  weeks  in 
close  vessels  ;  but  in  a  dilute  syrup,  exposed  to  the  air  and 
protected  from  dust,  traces  of  altered  sugar  may  be  found 
in  three  days,  which  increase  from  day  to  day. 

*  Compt.  Rend.,  xl.  436.  \  Journ.  Prak.  Chemie,  ciii.  449. 

J  Amer.  Chemist,  vi.  217. 


INVERSION  BY  WATER.  45 

Solutions  of  cane-sugar  brought  into  intimate  contact 
with  the  air  alter  very  quickly.  In  an  experiment  where  a 
solution  of  sugar  of  10°  B.  was  caused  to  flow  over  bits  of 
broken  glass  in  a  cylinder  open  at  both  ends,  at  19°C.  it 
was  found  that  traces  of  invert-sugar  could  be  discovered 
after  six  hours.  The  alteration  after  this  time  went  on 
with  greater  proportionate  rapidity,  so  that  scarcely  any 
crystallizable  sugar  remained  after  thirty-six  hours 
(Hochstetter*).  When  nitrogenous  matter  is  present  a  few 
hours  suffice  for  the  above  change.  The  best  authorities 
admit  that  the  formation  of  levulose  and  dextrose  in  inver- 
sion is  simultaneous.  Clasen(Zoc.  cit.)  states  that  a  dilute 
solution  of  cane-sugar  heated  immediately  after  its  pre- 
paration, nearly  to  the  boiling-point  of  water  for  several 
hours,  takes  on  no  molecular  change.  According  to  Hoch- 
stetter,  a  solution  of  cane-sugar  of  25°  B.,  boiled  in  a  dish 
for  one,  one  and  a  half,  and  two  hours,  at  110°  to  112°,  un- 
derwent but  slight  inversion ;  but  on  passing  air  into  the 
boiling  solution  the  action  took  place  with  much  greater 
rapidity.  Lund  ascribes  this  change  to  the  carbonic  acid 
present  in  the  air. 

ACTION   OF  ACIDS — INVERSION. 

This  change  is  produced  in  perfection  by  the  action  of 
dilute  acids  on  cane-sugar  solutions  ;  the  mineral  acids  act 
more  quickly  and  powerfully  than  others.  The  change 
takes  place  at  ordinary  temperatures,  but  much  quicker  in 
the  heat  and  as  the  acid  is  more  concentrated.  If  the 
heating  is  long  continued  after  the  inversion  is  complete, 
coloration  of  the  solution  takes  place,  accompanied  with 
the  formation  of  various  humus  and  ulmic  compounds.  If 

*  Jour,  fur  Prak.  Chemie,  1843. 


46  CANE-SUGAR  OR  SACCHAROSE. 

a  solution  of  sugar  is  heated  with  dilute  sulphuric  acid  to 
a  temperature  below  100°  C.,  ulmin  and  ulmic  acid  make 
their  appearance,  which,  if  the  solution  is  brought  to  ebul- 
lition, are  mixed  with  humin  and  humic  acid  ;  on  the  aver- 
age not  more  than  one-sixth  of  the  sugar  can  be  converted 
into  these  compounds,  the  rest  remaining  in  solution  as 
glucic  acid,  and,  if  the  air  has  had  free  access,  apoglucic 
acid  is  also  present.  The  humus  substances  are  produced 
at  the  boiling-point  in  vacuo  (Mulder).  Nitric  and  hydro- 
chloric acids,  as  well  as  sulphuric  acid,  produce  the  humus 
decomposition  of  sugar  ;  for  every  one  part  of  these  acids 
ten  parts  of  oxalic,  racemic,  tartaric,  citric,  or  saccharic 
acids,  and  sixteen  parts  of  phosphoric,  arsenious,  arsenic, 
and  phosphorous  acids,  are  required  to  produce  the  same 
effect ;  the  acid  remains  unaltered  arid  may  be  recovered 
(Malaguti,  Ann.  Cliim.  Pliys.,  lix.  416). 
*  The  relation  of  various  acids  to  the  phenomena  of  inver- 
sion has  been  studied  by  A.  Behr,  *  the  results  of  whose 
experiments  are — viz.  : 

I.  Effect  of  quantity  of  acid  and  concentration. — For 
the  same  quantity  of  sugar  the  increase  of  inversion  is  by 
no  means  proportional  to  the  increase  in  the  amount  of 
acid  present ;  while  it  appears,  on  the  other  hand,  for  a 
fixed  quantity  of  acid,  that  the  inversion  bears  a  direct  rela- 
tion to  the  concentration  or  amount  of  sugar  present. 

II.  Effect  of  temperature. — Elevation  of  temperature  has 
an  enormous  influence  over  the  amount  of  inversion  pro- 
duced.     Also,   every  acid  has  a  specific  temperature  at 
which  the    alteration  begins  :   this  for  sulphuric  acid  is 
30°  to  40°  C.  ;  for  phosphoric  acid,  40°  to  50°  ;  and  for 
acetic  acid,  70°  to  80°. 


*  Zeits.  f.  Zuckerind.  des  Deut.  Reiches,  xxiv.  778. 


INVERSION. 


47 


III.  Effect  of  time. — Probably  the  time  during  which 
the  action  takes  place  is  in  direct  proportion  to  the  amount 
of  inversion. 

IV.  Effect  of  the  'kind   of  acid.— The  following  table 
shows  the  specific  influence  of  different  acids.     The  condi- 
tions of  the  experiments  are  the  same  in  each  case,  the 
solutions  being  pretty  concentrated,  and  the  amount  of 
acid  is  such  that  100  parts  of  sugar  have  a  quantity  of  acid 
chemically  equivalent  to  one  part  SO4H2.    In  the  columns 
headed  1,  2,  3,  the  time  of  the  reactions  and  the  tempera- 
tures were : 

1.  13°-18°  C.,  time  211  hours. 

2.  19°-27°  C.,     "     115     " 

3.  25°-27°  C.,     "      78     " 


Inversion,  per  cent. 

Inversion  relative  to  HC1  ; 
HC1  =  100. 

I. 

2. 

3- 

I. 

2. 

3- 

.88 

•97 
1.49 
1.56 
2-75 
6.32 
7.14 
7.14 
8.10 
10.41 
20.07 

41-34 
64.68 
77.84 
78.14 

1.29 
1.98 
2.05 

3-19 
7.07 

8.21 

7-76 
7-99 

II.  IO 

21.67 

43-95 
67.91 
80.68 
80.75 

1.2 

'V.a 

10.2 
II.4 
24.2 
49.6 

83-9 
IOO.O 
100.  1 

i-3 

1.9 

2.2 

3-5 
8.1 
9.2 
9-2 
10.4 

13-4 

25.8 
53-1 
83-1 

IOO.O 

100.4 

1.6 

2-5 

2.5 
4.0 

8.8 

10.2 
9.6 

9-9 

13-8 
26.9 

54-5 
84.2 

IOO.O 
IOO.I 

Isobutyric     ........ 

Malic       

5-9 

7-38 
8.19 
17.42 

35-79 
60.52 
72.10 
72.18 

Tartaric     

Oxalic    

Sulphuric    

Hydrochloric       .    . 

Nitric  

In  the   above   experiments  the  inversion   was   estimated 
optically,  the  invert-sugar  formed  being  calculated  by  the 

formula     p  =  20°9^)0  ~  P),  in  which 

Joo  —  t 


48  CANE-SUGAR  OR  SACCHAROSE. 

D  =  the  polarization, 
t    =  the  temperature. 

Lowenthal  and  Lenssen  *  have  also  experimented  upon 
this  subject,  and  some  of  their  results  differ  from  those 
given  above  ;  they  are  as  follows  : 

1.  The  action  is  proportional  to  the  quantity  of  cane- 
sugar  present.  2.  The  action  is  slower  the  more  dilute  the 
solution  up  to  a  certain  point,  but  beyond  that  the  case  is 
reversed.  3.  The  early  stages  of  the  reaction  proceed  more 
actively ;  all  monobasic  acids  modify  sugar  in  the  same 
degree.  Dubrunfaut  f  states  that  the  amount  of  inversion 
by  acids  is  directly  as  the  square  of  the  time,  and  for  a 
complete  inversion  the  time  required  is  proportional  to  the 
quantity  of  acid  ;  but,  on  the  other  hand,  there  is  no  simple 
relation  to  the  quantity  of  sugar  taking  part  in  the  reac- 
tion. According  to  Fleury,$  using  the  same  quantity  of 
acid  on  varying  quantities  of  sugar,  the  time  required  for 
complete  inversion  is  constant ;  the  results  obtained  by 
him  are  expressed  by  the  curve 

—  a?, 

in  which  K  is  a  coefficient  depending  on  the  temperature 
and  the  nature  of  the  acid,  and  (a)  is  a  function  of  the 
amount  of  acid. 

Y.  Lippman  has  investigated  the  inversion  of  cane-sugar 
by  carbonic  acid  gas,  and  finds  that  a  sugar  solution  satu- 
rated with  the  gas  and  polarizing  100°,  after  standing  150 
hours  showed  a  rotation  of  — 44.2°,  being  completely  in- 
verted. The  same  authority  also  found  the  invertive  action 
to  be  considerably  increased  by  pressure,  a  solution  at  100°, 

*  Journ.  Prak.  Chemie,  Ixxxv.  021.  $  Compt.  Rend.,  Ixxxi.  823. 

f  Journ.  Fabr.  Sucre,  xiii.  No.  21. 


ACTION  OF  SULPHURIC  ACID.  49 

saturated  with  the  gas  and  heated  under  pressure,  being 
entirely  inverted  in  from  twenty  to  thirty  minutes. 

Bodenbender  and  Berendes*  find  that  sulphurous  acid 
inverts  cane-sugar  largely,  especially  in  the  heat,  with  the 
formation  of  sulphuric  acid,  and  that  the  presence  of 
citrates,  lactates,  formiates,  and  benzoates  lessens  this 
action ;  citric  acid  may  entirely  prevent  it  when  the 
amount  of  the  sulphurous  acid  is  no  greater  than  sufficient 
to  saturate  the  base  combined  with  the  organic  acid. 

Hydrochloric  acid  in  the  cold  forms  only  dextrose  (Neu- 
bauer  f).  Acids  of  the  aromatic  series  and  salicylic  acid 
invert  strongly  (Pellet  and  Pasquier  f). 

Action  of  Sulphuric  Acid. — Cold  oil  of  vitriol  forms 
a  mixture  with  cane-sugar  completely  soluble  in  water 
without  separation  of  carbon ;  if  the  solution  is  diluted, 
neutralized  with  chalk,  and  evaporated  to  dryness,  it 
yields  a  dark-brown  residue  containing  sulphur  (Bracon- 
not  §).  Mulder,  [|  on  heating  cane-sugar  with  dilute  sul- 
phuric acid,  found  that  glucic  acid  C18H18O9  and  apoglucic 
acid  C24H26O13  were  formed.  See  also  Richard  (Zeit.f.  Ru- 
~benz.,  xx.  529). 

By  the  action  of  sulphuric  acid  on  sugar  Grothe  and 
Tollens  1"  have  produced  a  compound  which  they  call  lemi- 
linic  acid ;  this  acid  has  the  formula  CBH8O3,  and  is  pro- 
duced by  the  decomposition  of  the  levulose  formed  from 
the  cane-sugar  by  inversion  ;  the  equation  below  represents 
the  ultimate  reaction : 

C12H22On   =   C.HM0.  +  C6H803  +  CH202. 

Dextrose.     Levulinic  acid.    Formic  acid. 

*  Zeit.  f.  Rubenz.,  xxiii.  21.  §  Ann.  Cliim.  Phys.,  xii.  189. 

f  Fres.  Zeitsclirift,  xv.  188.  ||  Ann.  der  Chemie,  xxxvi.  243. 

\  Jour.  Fabr.  Sucre,  xviii.  No.  33.       H  Ibid  ,  clxxv.  No.  1,  2. 


50  CANE-SUGAR  OR  SACCHAROSE. 

In  the  heat  sulphuric  acid  acts  powerfully  on  cane-sugar, 
decomposing  it,  with  evolution  of  sulphurous  acid,  and 
leaving  a  voluminous  porous  coal. 

Hydrochloric  acid  gas  is  slowly  absorbed  by  cane- 
sugar,  which  is  converted  into  a  brown  product  containing 
the  elements  of  the  acid  ;  a  concentrated  solution  of  the 
gas  acts  violently  and  chars  the  sugar,  with  formation  of 
ulmic  acid.* 

Phosphoric  acid,  when  distilled  with  cane-sugar,  pro- 
duces formic  acid  and  a  volatile  oil.  Oxalic  acid  heated 
with  an  equal  weight  of  cane-sugar,  and  the  mixture  dis- 
tilled, yields  formic  and  carbonic  acids  in  small  quantity, 
and  a  brown  body  similar  to  the  Tiumin  of  Mulder  (Van 
Kerckhoff,  Journ.  PJc.  Chemie,  Ixix.  48).  Tartaric  acid  act- 
ing on  cane-sugar  at  100°  forms  saccharoso-tetratartaric 
acid,  which  reduces  Fehling's  solution  and  appears  to 
contain  modified  saccharose  (Berthelot).  The  acids  stea- 
ric,  butyric,  acetic,  and  'benzole,  heated  with  cane-sugar, 
furnish  products  resembling  those  obtained  from  dextrose 
under  similar  circumstances. 

Action  of  Oxidizing  Agents.  —  Nitric  acid,  or  a  mix- 
ture of  nitric  and  sulphuric  acids,  acting  on  sugar,  pro- 
duces a  nitro-substitution  compound,  xyloidin,  which 
separates  as  a  tough  mass  and  inflames  in  contact  with  a 
red-hot  coal.  Dilute  nitric  acid  gives  rise  to  the  formation 
of  saccharic  and  oxalic  acids.  One  part  of  cane-sugar 
with  three  parts  of  nitric  acid  of  sp.  gr.  1.25  to  1.30, 
heated  to  50°,  is  entirely  transformed  into  saccharic  acid 
and  water  : 


*  Mulder,  Journ.  PJc.  Chem  ,  xxi.  203  ;  xxxii,  331. 


OXIDIZING  AGENTS.  51 

At  a  higher  temperature  oxalic  acid  is  chiefly  formed  after 
long-continued  heating  with  excess  of  acid.*  By  distilla- 
tion wiihpe?~oxide  of  manganese  and  sulphuric  acid  cane- 
sugar  yields  formic  acid  and  a  strongly-smelling  oil.  Boil- 
ing with  peroxide  of  lead  or  acid  potassium  cliromate 
gives  formic  and  carbonic  acids.  Mixed  with  chlorate  of  po- 
tassium, and  struck  sharply  or  touched  with  a  drop  of  oil  of 
vitriol,  cane  sugar  explodes.  PERMANGANATE  OF  POTAS- 
SIUM oxidizes  sugar  readily  in  acid  solution,  resolving  it 
into  carbonic  acid  and  water.  Maumene  has  obtained  two 
acids,  liexepic  C0HI2O8  and  trijienic  C3H,Ob,  by  the  action 
of  potassium  permanganate  on  sugar.  To  prepare  them, 
equal  parts  of  sugar  and  the  salt  are  dissolved  in  thirty  to 
forty  parts  of  water  separately,  and  the  solutions  mixed 
in  the  cold,  with  agitation ;  heat  is  disengaged,  and  the 
manganese  peroxide  separates  in  a  lump,  and  the  clear, 
colorless  solution  contains  the  acids.  Hexepic  acid  pos- 
sesses a  rotatory  power  equal  to  cane-sugar,  and  its  solu- 
tion is  precipitated  by  acetate  and  subacetate  of  lead. 
Both  acids  form  crystallizable  salts.  Hexepate  of  potas- 
sium is  but  little  soluble ;  the  trijienates  of  sodium,  lead, 
and  copper  form  small  crystals.  Maumene  has  found 
these  acids  ready  formed  in  a  great  number  of  plants,  es- 
pecially those  yielding  sugar. 

Chlorine  is  absorbed  by  sugar,  forming  an  odorous,  de- 
liquescent mass  which  gives  oif  hydrochloric  acid.  When 
chlorine  is  passed  into  sugar  solutions  there  is  obtained, 
together  with  uncrystallizable  compounds,  a  new  acid  free 
from  chlorine,  the  barium  salt  of  which  is  crystallizable. 
Malic  acid  is  also  said  to  be  formed.  Hlasiwetz  and  Haber- 
man  (Ber.  Chem.  Gesell.,  iii.  486)  have  shown  that  chlorine 

*  See  also  Liebig,  Ann.  der  Chem.,  cxiii.  1. 


52  CANE-SUGAR  OR  SACCHAROSE. 

acting  on  sugar  gives  rise  to  gluconic  acid  C6H12O7.  Per- 
chlorides  act  on  sugar  in  the  same  manner  as  chlorine, 
producing  dark -colored  products.  Maumene  *  makes  use 
of  this  fact  as  a  basis  for  a  qualitative  test  to  detect  cane- 
sugar  and  analogous  substances.  A  drop  of  the  liquid  to 
be  examined  is  placed  on  a  strip  of  white  merino  pre- 
viously steeped  in  a  solution  of  stannic  chloride,  and 
dried.  After  the  addition  of  the  sugar  solution  the  me- 
rino is  warmed  over  a  lamp,  and  the  presence  of  saccha- 
rine or  saccharoidal  matter  is  indicated  by  the  appearance 
of  a  black  spot.  Iodine  and  bromine  act  on  cane-sugar  in 
the  same  way  as  chlorine,  with  production  of  gluconic 
acids  (Grieshammer,  CJiem.  Centb.,  No.  44).  When  equi- 
valent quantities  of  potassium  bicarbonate  and  iodine  are 
added,  one  after  another,  to  an  aqueous  solution  of  cane- 
sugar,  iodoform  is  produced  on  boiling  (Millon,  Compt. 
Mend.,  xix.  271). 

OXYGEN,  or  air,  and  especially  ozonized  air,  passed  over 
dry  cane-sugar  or  through  the  aqueous  solution  at  com- 
mon temperatures,  gives  rise  to  carbonic  acid  and  water 
from  a  small  part  of  the  sugar,  while  the  rest  is  unacted  on. 
Ozone  produces  no  change  in  a  neutral  aqueous  solution 
of  cane-sugar,  but  when  carbonate  of  sodium  is  present 
the  sugar  is  slowly  but  completely  oxidized  to  carbonic 
and  formic  acids  (Gorup-Besanezf).  Arsenic  acid  oxi- 
dizes cane-sugar,  a  red  color  being  developed  owing  to 
the  formation  of  humus  compounds.  Eisner  proposes  the 
following  as  a  qualitative  test  to  detect  cane-sugar :  A  so- 
lution containing  one-thirtieth  part  of  saccharose,  heated 
in  steam  with  a  one  per  cent,  solution  of  arsenic  acid,  in  a 

*  Traite.  f  Ann.  der  Chem.,  cxxv.  211. 


ACTION  OF  CUPRIC  SALTS.  53 

small  dish,  becomes  red  at  the  margin,  and  on  evaporation 
yields  a  red  spot. 

With  CUPRIC  SALTS,  sugar  is  slightly  oxidized,  the  ex- 
tent of  the  reaction  varying  with  the  conditions,  such 
as  whether  the  solutions  are  heated  or  not,  the  presence 
of  caustic  alkalies,  etc.  Cupric  hydrate  preserves  its 
color  when  left  to  stand  in  the  cold,  or  when  boiled  a  short 
time  with  cane-sugar  ;  but  after  longer  boiling  it  gives  up 
its  water,  turns  brown,  and  is  reduced  to  yellow  cuprous 
oxide.  If  the  solution  contains  a  trace  of  alkali  the  hy- 
drate dissolves  immediately,  and  is  then  precipitated  by 
the  sugar.  When  cupric  hydrate,  washed  with  cold  water, 
is  boiled  with  cane-sugar  solution  and  a  little  caustic  al- 
kali, the  colorless  liquid  filtered  from  the  precipitated 
cuprous  oxide  contains  oxalic,  carbonic,  and  acetic  acids. 
Sugar  boiled  with  aqueous  cupric  sulphate  throws  down 
metallic  copper,  while  a  quantity  of  cuprous  salt  remains 
dissolved  (Vogel).  A  solution  of  equal  parts  sugar  and 
cupric  sulphate,  and  a  sufficient  excess  of  caustic  alkali, 
retains  its  blue  color  unaltered  in  the  cold  for  several 
days,  and  deposits  a  small  quantity  of  red  oxide  only 
after  some  weeks.  The  reduction  does  not  take  place 
until  after  some  time,  even  on  boiling  (Trommer*).  When 
saccharose  is  boiled  with  cupric  chloride,  the  liquid,  on 
cooling,  deposits  cuprous  chloride,  if  sufficiently  concen- 
trated. From  cupric  acetate  a  large  quantity  of  cuprous 
oxide  containing  organic  matter  is  thrown  down,  while  a 
deliquescent  sugar  remains  dissolved  (Vogel  f). 

If  a  concentrated  solution  of  cane-sugar  is  mixed  with 
cobaltic  nitrate,  a  small  quantity  of  fused  caustic  soda 
added,  and  the  solution  boiled,  a  violet-blue  precipitate  is 

*  Ann.  P7mrw.,xxxix.  360.  f  Schweigger's  Journal,  xiii.  102. 


54  CANE-SUGAR  OR  SACCHAROSE. 

formed.  The  presence  of  a  very  small  amount  of  dextrose 
prevents  the  reaction. 

Action  of  Alkalies. — Caustic  alkalies,  their  carbon- 
ates, and  the  oxides  of  the  alkaline  earths  all  act  more 
or  less  powerfully  on  cane-sugar.  The  oxides  generally 
form  compounds  called  sucrates,  in  which  the  sugar  acts 
the  part  of  an  acid. 

AMMONIA. — According  to  Laborde,*  on  passing  a  cur- 
rent of  dry  ammonia  gas  over  perfectly  anhydrous  sugar, 
it  becomes  at  first  opalescent,  and  then  takes  on  the  waxy 
consistency  described  by  Raspail ;  in  the  course  of  twelve 
hours  it  liquefies,  and  contains  then  7.83  per  cent,  ammo- 
nia. Dextrose  similarly  treated  liquefies  very  quickly  and 
becomes  colored,  forming  a  crystalline  compound.  Cane- 
sugar  heated  with  aqueous  ammonia  in  sealed  tubes  for 
forty  hours  to  180°  C.  produces  an  insoluble  black  sub- 
stance of  undetermined  composition,  f 

SODA  AND  POTASH. — Cane-sugar  triturated  with  the 
fixed  caustic  alkalies,  or  strong  solutions  of  them,  is  not 
colored  brown,  and  this  distinguishes  it  from  dextrose.  If 
cane-sugar  be  heated  with  caustic  potash  and  a  little 
water,  the  mass  evolves  hydrogen  and  is  found  to  contain 
a  large  quantity  of  potassium  oxalate  (Gay  Lussac).  The 
mass,  on  distillation  with  sulphuric  acid,  yields  carbonic, 
formic,  and  acetic  acids  and  metacetone.  Caustic  alkalies 
and  alkaline  carbonates  mixed  with  sugar  diminish  its 
rotatory  power,  not  in  proportion  to  the  quantity  of  base 
present,  but  according  to  the  concentration  of  the  solu- 
tions. From  such  mixtures  the  sugar  may  be  obtained 
with  its  original  optical  rotation  by  treatment  with  car- 

*  Compt.  Rend ,  Ixxviii.  82. 

f  Schutzenberger,  Ann.  CJiim.  Phys.,  iv.  65. 


CAUSTIC  LIME. 

Vc7V*;> 

bonic  acid,  the  alkaline  bicarbonates  formed  having  no 
effect  on  the  polarized  ray  (Sostman  *).  By  boiling  solu- 
tion of  cane-sugar  for  seventy- two  hours  with  one-fiftieth 
part  crystallized  sodium  carbonate,  an  acid  black  liquid  is 
produced  possessing  levo-rotatory  power  (Soubeiran). 

CAUSTIC  LIME. — Bouchardat  and  Soubeiran  have  found 
that  solutions  of  cane-sugar  mixed  with  hydrate  of  lime 
exhibit  greater  stability,  when  boiled  or  long  kept,  than 
pure  aqueous  solutions.  If  a  solution  of  sugar  super- 
saturated with  lime  is  allowed  to  stand  for  a  year  in  a 
tight  bottle,  the  excess  of  lime  contains  neither  oxalic  nor 
malic  acids.  After  removing  the  dissolved  lime,  evaporat- 
ing to  dryness,  and  redissolving  in  alcohol,  cane-sugar 
crystallizes  out  from  the  alcoholic  solution,  while  melassic 
and  saccJiaric  acids,  and  uncrystallizable  sugar  remain  in 
the  mother  liquor  (Brendecke).  An  intimate  mixture  of 
one  part  cane-sugar  and  three  parts  quicklime,  heated, 
produces  a  violent  reaction,  acetone  and  metacetone  being 
evolved.  On  distillation  of  sugar  with  caustic  lime  there 
are  produced  acetone,  metacetone,  isophorone,  and  marsh- 
gas,  with  small  quantities  of  carbide  of  ethylene. 

SUCEATES. 

Potassium  Sucrate.f — CianaiKOn  \  is  formed  as  a  gela- 
tinous precipitate  by  adding  caustic  potash  to  a  strong 
solution  of  sugar  in  alcohol.  It  is  white,  friable  (Sostman 
says  it  cannot  be  dried),  and  translucent ;  melts  at  100° 
to  a  viscid  liquid  having  an  alkaline,  not  sweet  taste ; 

*  Zeit.  f.  Rubenz.,   xxii.  173. 

f  Authorities  :  Peligot  (Ann.  Chim.  Phys.,  [2]  Ixvii.  113  ;  ibid.,  Ixxiii.  103  ; 
ibid.  [3]  liv.  377).  Soubeiran  (Journ.  de  Pharm.  i.  469).  Berthelot  (Ann.  Chim. 
Phys,  [3]  xlvi.  173). 


56  CANE-SUGAR  OR  SACCHAROSE. 

completely  decomposed  by  carbonic  acid,  the  sugar  being 
recovered  unaltered. 

Potassium  Hydric  Sucrate. — To  a  hot  saturated  solution 
of  sugar  an  equal  bulk  of  strong  nitric  acid  is  added,  and 
the  mixture  kept  warm  until  the  evolution  of  gas  has 
ceased,  when  it  is  boiled.  The  liquid  is  then  divided  into 
two  equal  parts,  one  of-  which  is  neutralized  with  caustic 
potash  and  added  to  the  other,  when  an  abundant  precipi- 
tation of  the  sucrate  takes  place  ;  this,  if  colored,  may  be 
purified  by  filtration  over  animal  charcoal,  evaporation, 
and  recrystallizing  (Bayley,  CJiem.  News,  xliii.  110). 

Sodium  Sucrate  (C]2H21NaOn  1) — Similar  in  all  respects 
to  the  potassium  compound. 

Calcium  Sucrates.* — Lime  combines  with  saccharose 
in  different  proportions,  forming  combinations  whose  chem- 
ical constitution  is  mostly  well  marked.  The  quantity  of 
lime  dissolved  by  sugar  solutions  depends  on  their  density 
and  the  temperature  at  which  the  solution  takes  place  ;  this 
for  100  parts  of  sugar  varies,  under  these  circumstances, 
from  23  to  55  parts.  When  excess  of  lime  is  agitated  with  a 
sugar  solution,  saturation  takes  place  but  slowly,  and  only 
when  the  quantity  of  the  base  is  at  least  t'yice  as  great  as 
the  solution  will  take  up.  Strong  solutions  (above  30  per 
cent.)  become  gummy  and  solidify,  while  with  more  di- 
lute solutions  monobasic  sucrate  is  formed ;  but  this  is 
capable  of  taking  up  an  additional  quantity  of  lime, 
greater  in  proportion  as  the  solution  is  more  concentrat- 
ed. Cane-sugar  solutions  of  40  per  cent,  dissolve  26.57 

*  Authorities  :  Soubeiran (Journ.  de  Pharm.,  i.  469).  Peligot  (Compt.  Rend., 
xxxii.  333  ;  Ann.  Chim.  Phys.,  [3]  liv.  377  ;  Compt.  Rend.,  lix.  930).  Berthelot 
(Ann.  Chim.  Phys.,  [3]  xlvi.  173).  Pclouze  (Compt.  Rend.,  lix.  1073).  Boivin  et 
Loiseau  (Compt.  Rend.,  lix.  1073  ;  ibid.,  Ix.  164,  454  ;  Ann.  Chim.  Phys.,  [4]  vi. 
203).  Horsin-Deon  (Bull.  Soc.  Chim.,  1371,  xvi.  26  ;  ibid.,  xvii.  155). 


CALCIUM  SUCRATES.  ,j7 

parts  of  Hme  to  100  parts  of  sugar ;  solutions  of  20  per 
cent,  take  up  23.15  parts;  and  5  per  cent,  solutions  dis- 
solve 18.06  parts  (Peligot). 

Solution  of  calcic  sucrate  has  a  bitter  and  alkaline  taste. 
The  specific  rotatory  power  of  the  sugar  combined  with 
lime  is  less  than  in  the  free  state  (see  page  176).  On  neu- 
tralization with  acid  the  rotatory  power  is  restored,  even  if 
the  solution  of  the  sucrate  has  been  heated  to  117.5°,  but 
not  if  heated  higher  (Dubrunfaut).  A  solution  of  calcic 
sucrate  considerably  diluted  forms  a  gelatinous  mass  on 
heating ;  on  cooling,  or  the  addition  of  sugar,  the  solution 
is  cleared  up. 

According  to  Bodenbender,  *  the  aqueous  solution  of 
sucrate  of  lime  dissolves  certain  metallic  oxides  in  the  pre- 
sence of  excess  of  the  sucrate.  The  following  table  repre- 
sents the  amount  of  the  oxides  taken  up  by  sucrate  solu- 
tion of  various  strengths.  A  is  a  solution  containing  in 
one  litre  418.6  grm.  sugar  and  34.3  grm.  lime ;  B  contains 
296.5  grm.  sugar  to  24.2  grm.  lime ;  and  C  174.4  grm. 
sugar  to  14.1  grm  lime  : 


A. 

B. 

C. 

MgO   Grammes. 

.^o 

.24 

.22 

A12O3 

I  ^ 

^2 

.19 

Fe2O3   

6  26 

4.71 

3.08 

Mn2O3  

*9/O 

•  37 

.32 

Cr2O3        

I  O7 

56 

,2O 

CoO    

i  ^6 

I.OO 

.CO 

NiO  

.20 

ZnO  

.24. 

CdO  

.22 

.48 

CuO 

10  26 

*  68 

0.47 

The  solutions,  on  standing,  deposit  lime  and  the  oxide. 


*  Zeits.  f.  Zuckerind.  Deut.  Reiches,  1865,  851-860. 


58  CANE-SUGAR  OR  SACCHAROSE. 

An  aqueous  solution  of  lime  sucrate  dissolves  recently-pre- 
cipitated phosphate  and  carbonate  of  lime. 

Only  dilute  solutions  of  the  sucrate  become  turbid  on 
exposure  to  the  air;  carbonic  acid  gas  slowly  but  com- 
pletely precipitates  the  base,  yielding  the  sugar  unaltered. 
When  the  solutions  have  been  prepared  in  the  cold  no 
traces  of  invert-sugar  can  be  detected  by  boiling  with  alka- 
line solution  of  oxide  of  copper.  According  to  Hochstetter, 
even  if  the  solution  is  boiled  on  the  open  fire  for  two  hours 
till  the  mass  begins  to  thicken  and  char,  the  unburnt  por- 
tion still  yields  the  sugar  unaltered. 

Monobasic  Sucrate.  C12H22On  CaO. — Prepared  by  add- 
ing 85  per  cent,  alcohol  to  a  concentrated  solution  of  sugar 
containing  excess  of  lime.  It  is  a  white  precipitate,  drying 
to  a  brittle  resin,  which  deflagrates  after  drying  and  dis- 
solves easily  in  cold  water ;  the  solution,  when  heated,  de- 
posits tribasic  sucrate  and  sets  free  some  sugar. 

3(C12HSJOn  CaO)  =  C13HsaO,,  3CaO  +  2C.AA, 

(Peligot). 

S.  Benedikt  *  prepares  this  cbmpound  by  adding  magne- 
sium chloride  to  a  sucrate  containing  excess  of  lime,  filter- 
ing, and  treating  the  filtrate  with  excess  of  alcohol ;  the 
precipitate  produced  is  washed  with  warm  60  per  cent, 
alcohol.  Dried  at  100°,  the  deposit  has  the  formula 
C12H20CaOn  ;  dried  in  a  vacuum  at  ordinary  temperatures, 
two  molecules  of  water  are  retained. 

Bibasic  Sucrate.  C12H22On  2CaO. — Boivin  and  Loiseau 
(loc.  cit.)  have  obtained  this  compound  (1)  by  agitating 
finely-divided  hydrate  of  lime  with  a  solution  of  cane-sugar, 
and  cooling  to  0°  ;  (2)  by  treating  the  tribasic  sucrate  with 

*  Bull.  Soc.  CMm.,  xx.  279. 


CALCIUM  SUCRATES.  59 

sugar  and  lime  ;  (3)  by  precipitating  in  the  cold,  by  alcohol 
of  65  per  cent.,  a  solution  of  lime  and  sugar,  and  boiling. 
Water  decomposes  this  sucrate  into  the  tribasic  salt  and 
cane-sugar.  The  compound  C12H22On  2CaO  |H2O  is  said  to 
be  obtained  by  precipitating  a  solution  of  sugar-lime  by 
alcohol. 

Sesquibasic  Sucrate.  2CI2H22On  3CaO.— This  is  always 
formed  when  a  solution  of  sugar  with  excess  of  lime  is 
boiled,  or  set  aside  at  ordinary  temperatures ;  the  com- 
pound may  be  obtained  as  a  white  amorphous  gum  by.  eva- 
porating the  filtrate  in  an  atmosphere  of  carbonic  acid  gas. 
It  is  a  transparent,  resinous  or  granular,  white,  friable  mass, 
which  deflagrates  and  readily  dissolves  in  cold  water ;  inso- 
luble in  strong  and  weak  alcohol,  but  soluble  in  an  alco- 
holic solution  of  cane-sugar. 

Tribasic  Sucrate.  C]2H22OU  3CaO.  C12H22O12  3CaO.3H2O.* 
-This  separates  as  a  mass  resembling  coagulated  albumen, 
when  a  sugar  solution  containing  excess  of  lime  is  heated 
and  filtered.  It  is  soluble  in  100  parts  of  cold  water,  the 
solution  when  heated  depositing  half  the  quantity  dis- 
solved ;  it  is  readily  soluble  in  sugar- water  (Peligot,  loc. 
cit) 

Sexbasic  Sucrate.  C12H2QOn  6CaO. — According  to  Horsin- 
Deon,  a  salt  of  the  above  composition  is  obtained  by  treat- 
ing the  tribasic  sucrate  with  alcohol. 

Sucro-carbonates  of  Lime.f — When  carbonic  acid 
gas  is  passed  into  sugar- water  mixed  with  lime,  the  gas  is 
absorbed,  and  if  the  liquid  is  sufficiently  dense  a  gelatinous 
precipitate  is  formed  after  a  time  ;  by  the  continued  action 

*  Lippraan,  S.  Neue  Zeit.,  iv.  148. 

f  Dubrunfaut,  Compt.  Eend.,  xxxii.  498  ;  Boivin-Loiseau,  Butt.  Soc.  CTiim., 
xi.  345  ;  Horsin-Deon,  ibid.,  xv.  22  ;  xix.  65. 


50  CANE-SUGAR  OR  SACCHAROSE. 

of  the  gas  the  precipitate  is  decomposed  and  all  the  lime 
thrown  down.  If  the  solution  is  heated  the  compound  is 
likewise  decomposed,  but  some  lime  remains  in  solution. 
The  body  thus  formed,  having  the  formula  3C03Ca.C12H22On 
3CaO  2H2O,  is  the  Jiydrosucro-carbonate  of  lime  of  Boi- 
vin  and  Loiseau,  and  may  also  be  obtained  by  the  action 
of  carbonic  acid  on  the  sexbasic  sucrate.  According  to 
Horsin-Deon,  the  compound  3C03Ca.C12H22Ou  CaO  2H2O  is 
produced  under  other  circumstances  when  the  proportions 
of  water,  lime,  and  sugar  are  different  from  the  above.  The 
composition  of  the  sucro- carbonate,  however,  varies  with 
the  temperature,  density  of  the  solutions,  and  with  the 
varying  proportions  of  sugar  and  lime  ;  the  quantity  of 
carbonic  acid  absorbed  may  range  from  4.4  per  cent,  to 
16.28  per  cent.  Bondonneau  *  considers  the  sucro-carbon- 
ate  to  be  only  calcic  carbonate  in  a  gelatinous  condition, 
and  soluble  in  sucrate  of  lime. 

Sucrate  of  Baryta.    C12H22On  BaO. — Prepared  by  add- 
ing to  sugar  solution,  baric  hydrate  or  sulphide  : 

C12H22On  +  SBaS  +  H2O  =  BaOC12H22On  +  BaSH2S. 
It  consists  of  small  nacreous  crystals  resembling  boracic 
acid,  of  a  caustic  taste  and  alkaline  reaction  ;  after  drying 
in  vacua  it  does  not  give  off  water  at  200°  F.  Decomposed 
by  carbonic  acid,  it  gives  up  the  sugar  unaltered.  Soluble 
in  47.6  parts  of  water  at  15°,  and  43.5  parts  at  100°.  Inso- 
luble in  wood-spirit  and  alcohol.  The  formula  C12H22On 
2BaO  has  been  assigned  to  this  compound  by  Peligot, 
Stein,  and  others. 

Sucrates  of  Lead.f  (a)  Bibasic  C12H18Pb2On.— This  com- 
pound is  formed  when  finely -divided  litharge  is  boiled  with 

*  Bull.  Soc,  Chim.,  xxiii.  3. 

f  Boivin  et  Loiseau,  Compt.  Rend.,  1865,  60. 


METALLIC  SUCRATES.  61 

a  solution  of  sugar,  or  when  ammonia  is  added  to  a  solu- 
tion of  sugar  mixed  with  neutral  acetate  of  lead ;  it  is  in- 
soluble in  cold  water  and  alcohol,  and  soluble  in  boiling 
water,  crystallizing  out,  on  cooling,  in  nodules  or  needles. 
A  solution  of  the  tribasic  sucrate  left  to  stand  deposits  the 
bibasic  salt,  sugar  being  set  free,  (b)  Tribasic  C12H16Pb3On. 
—Prepared  by  adding  caustic  soda  or  potash  to  a  solution 
of  acetate  of  lead  and  sugar,  taking  care  not  to  have  an  ex- 
cess of  either  of  the  bodies  taking  part  in  the  reaction  ;  or  by 
mixing  a  solution  of  calcic  sucrate  with  a  boiling  solution 
of  acetate  of  lead.  It  is  a  white  powder,  insoluble  in  cold 
and  but  little  soluble  in  boiling  alcohol,  but  easily  soluble 
in  solutions  of  acetate  of  lead,  caustic  alkali,  or  cane-sugar. 
Metallic  lead  is  attacked  by  cane-sugar  solutions. 

Sucrate  of  Strontia  is  formed  by  adding  the  hydrate 
to  sugar-water. 

Ferrous  Sucrate  C12H22On  FeO. — When  metallic  iron 
is  partially  immersed  in  a  sugar  solution  it  rapidly 
corrodes.  The  red-brown  Solution  produced  yields,  on 
evaporation,  a  tasteless,  insoluble  residue  correspond- 
ing to  the  above  formula  in  composition.  It  is  in- 
soluble in  alcohol,  acted  on  by  ammonium  sulphide,  and 
not  by  alkalies  and  their  carbonates.  Sugar  solutions  do 
not  dissolve  ferrous  oxide,  and  have  but  slight  action  on 
ferric  oxide.  Ferric  hydrate  is  dissolved  by  a  solution  of 
sucrate  of  lime,  a  reduction  to  protoxide  taking  place.  By 
evaporation  a  double  salt  of  the  following  composition  is 

obtained : 

Fe02CaO  CHHMOn  3H20. 

Sucrates  of  Copper."51' — Copper  in  partial  contact  with 
the  air  dissolves  in  sugar-water.  Cupric  carbonate  is 

*Barreswill.  J,  dc  Pharm.,  iii  7,  29. 


62  CANE-SUGAR  OK,  SACCHAROSE. 

readily  soluble  in  the  same.  A  concentrated  solution  of 
cane-sugar  and  cupric  sulphate,  on  standing,  deposits  a 
bluish-white  precipitate  containing  SO4Cu  C12H22OU  4H2O. 

The  Double  Sucrate  of  Lime  and  Copper,  CuO 
CaOC12H22On  3H20,  is  obtained  by  evaporating  a  solution  of 
calcic  sucrate  in  which  cupric  oxide  has  been  dissolved. 
It  is  crystallizable  and  soluble  in  cold  water,  forming  a 
blue  liquid. 

Sucrate  of  Magnesia  is  formed  by  dissolving  the  hy- 
drate in  sugar- water.  All  of  the  magnesia  is  deposited 
from  the  solutions  on  standing. 

Hydrate  of  alumina  is  slightly  soluble  in  sugar  solution. 
Oxide  of  zinc  and  silica  are  insoluble.  Common  metallic 
zinc  in  contact  with  iron  is  dissolved  readily ;  but  very 
small  quantities  of  pure  tin,  zinc,  mercury,  or  silver  are 
dissolved  under  the  same  circumstances  (Gladstone*). 

COMBINATIONS   OF   CANE-SUGAK  WITH   NEUTEAL   SALTS.f 

With  Sodium  Chloride,  tC12H22On)2  NaCl6(H20)  (Mau- 
mene),  C12H22On  NaCl. — This  compound  is  deliquescent  and 
affected  by  heat  much  in  the  same  way  as  cane-sugar.  It 
has  a  sweet  saline  taste,  and  the  sugar  retains  its  rotatory 
power  unaltered.  Ch.  Yiolette  gives  the  formula  C12H20- 
NaClO,,,  and  considers  it  a  product  of  substitution.  If 
ether  is  added  to  an  alcoholic  solution  of  this  body,  an 
oleaginous  layer  separates,  which  deposits,  little  by  little, 
crystals  corresponding  to  the  formula : 

C12H22On  NaCl  2H20  (Gill,  loc.  cit.) 

Gill,  when  experimenting  with  cane-sugar  mixed  with  1,  2, 
3,  or  4  molecules  of  chloride  of  sodium,  found  the  crystals 

*  Journ.  Chem.  Soc.,  vii.  195.  f  Gill,  Journ.  Chem.  Soc.,  [2]  ix.  2C9. 


SALT  COMBINATIONS.  63 

were  always  of  variable  composition.     He  obtained  a  few 
crystals  having  the  composition: 


2C12H22On  SNaCl  4H20. 

With  Ammonium  Chloride  a  crystalline  compound 
of  cane-sugar  may  be  formed  containing  NH4C1,  but  the 
composition  is  not  invariable. 

With  Potassium  Chloride,  C12H22On  KCF,  crystallizes 
isomorphous  with  cane-sugar,  and  is  not  deliquescent. 
Gill  and  Maumene  were  not  able  to  obtain  this  combination 
of  invariable  composition. 

With  Bromide  of  Sodium,  C12H22On  BrNa  1JH20,  crys- 
tallizes with  difficulty  and  contains  varying  amounts  of 
water. 

With  Iodide  of  Sodium,  C12H22On3]SraI.3H20,  crystal- 
lizes well  in  the  monoclinic  system,  and  the  rotatory  power 
of  the  cane-sugar  contained  is  not  altered.  The  composi- 
tion is  constant,  no  matter  in  what  proportions  the  compo- 
nents are  mixed  (Gill). 

Lithium  chloride,  bromide,  and  iodide  do  not  form  defi- 
nite compounds  with  cane-sugar.  Acetate,  nitrate,  and 
phosphate  of  sodium  also  do  not  appear  to  combine  with 
cane-sugar. 

With  Borax,  3C12H22On]S"a2B407.5H20.—  When  borax  is 
dissolved  in  solution  of  sugar  and  the  liquid  evaporated, 
the  salt  first  crystallizes  out.  On  precipitating  the  mother- 
liquor  with  alcohol  a  glutinous  liquid  is  thrown  down, 
which,  after  solution  in  a  small  quantity  of  water,  and  pre- 
cipitation with  alcohol,  yields  a  compound  of  the  above 
composition  (Sturenberg,  ArcMv.  der  PTiarm.^  xviii.  27). 


64  CANE-SUGAR  OR  SACCHAROSE. 

MELASSIGENIC    ACTION    OF    SALTS    AND   ORGANIC    MATTERS 
ON   SUGAR  IN   SOLUTION. 

Melassigenic  action  consists  in  the  formation  of  molas- 
ses, which  is  a  residue  of  cane-sugar  solutions  from  which 
all  sugar  capable  of  crystallizing  has  been  obtained.  The 
loss  of  crystallizing  power  through  the  action  of  salts  may 
occur  in  two  ways :  (a)  either  ~by  an  invertive  action  causing 
the  cane-sugar  to  be  transformed  into  invert-sugar,  or  (b) 
by  a  specific  effect,  different  for  each  salt,  whereby  tliey 
retain  the  sugar  in  solution  without  altering  its  cliemical 
constitution.  The  lowest  molasses  of  commerce,  from 
which  all  sugar  has  been  crystallized  that  it  is  practicable 
to  get,  will  retain  from  25  to  30  per  cent,  cane-sugar  to 
about  an  equal  quantity  of  invert-sugar. 

A.  The  invertive  Action. — Some  neutral  salts  have 
the  power  of  inverting  cane-sugar,  either  by  their  decom- 
position, setting  free  acids  or  forming  acid  salts,  or  by  a 
specific  agency.  Bechamp*  has  made  some  experiments 
on  this  subject,  but  his  results  should  be  received  with 
some  caution,  from,  the  fact  that  the  sugar  solutions  upon 
which  he  worked  were  in  contact  with  the  air  from  seven 
to  eight  months,  by  which  mould  may  have  been  formed, 
and  the  inversion  ascribed  to  the  salts  have  been  caused  by 
the  presence  of  fungi.  Further,  Bechamp  measured  the 
inversion  by  the  lowering  of  the  optical  rotation ;  but  as 
some  of  the  salts  themselves  have  a  similar  action  on  the 
polarized  ray,  the  optical  means  cannot  be  relied  upon  for 
the  purpose  to  which  it  was  applied.  The  following  are 
Bechamp' s  results:  Aqueous  solutions  of  sugar  mixed 
with  zinc  sulphate,  plumbic  nitrate,  monophosphate,  or 

*  Ann.  Ctiim.  Phys.,  liv.  28. 


INVERSION  BY  SALTS.  65 

arseniate  of  potassium,  or  with  a  large  quantity  of  mer- 
curic chloride,  lose  their  rotatory  power  partially  or  entire- 
ly by  standing  at  ordinary  temperature,  and  occasionally 
acquire  a  rotation  to  the  left,  without  formation  of  mould. 
A  sugar  solution  containing  one-fourth  of  its  weight  of 
fused  chloride  of  zinc  or  calcium  hardly  decreases  in  rota- 
tary  power  in  standing  nine  months,  or  when  heated  for 
an  hour  to  50°.  The  presence  of  small  quantities  of  cor- 
rosive sublimate,  zinc  nitrate,  and  neutral  or  acid  potas- 
sium sulphate  prevents  the  formation  of  mould.  Most 
other  salts,  as  well  as  nitric  and  arsenic  acids,  do  not  hin- 
der the  formation  of  mould  in  sugar  solutions,  and  in 
general  the  decomposition  from  this  cause  goes  on  more 
rapidly  in  their  presence.  If  cane-sugar  solutions  are 
mixed  with  neutral  or  acid  sodium  sulphate  and  one  drop 
of  creosote,  no  appearance  of  decomposition  takes  place 
on  standing ;  but  the  growth  of  fungi  having  once  com- 
menced, creosote  has  no  power  to  arrest  it.  So  far  Be- 
champ.  W.  L.  Clasen  *  has  more  recently  made  similar 
researches  to  those  of  the  French  chemist,  in  which  he  has 
avoided  the  sources  of  error  inherent  to  the  method  of  the 
latter.  Fehling's  copper  test  was  used  in  connection  with 
the  saccharimeter  to  estimate  the  presence  of  invert-sugar, 
and  the  solutions  were  never  allowed  to  stand  more  than 
five  days,  precluding  the  possibility  of  mould  forma- 
tion. The  following  are  the  conclusions  based  on  his 
experimental  results :  (I)  Some  salts  at  ordinary  tempera- 
tures hinder  the  formation  of  in  vert- sugar,  as  sulphate  of 
lime,  ammonic  chloride,  and  potassium  nitrate  ;  others,  as 
magnesium  sulphate,  weaken  the  agency  of  water  in  invert- 
ing, though  they  are  not  entirely  able  to  prevent  it.  (2)  If 

*  Journ.  f.  Prak.  Chemie,  ciii.  449 ;  American  Chemist,  iv.  89. 


66  CANE-SUGAR  OR  SACCHAROSE. 

cane-sugar  solutions  mixed  with  certain  salts,  after  stand- 
ing several  days  at  ordinary  temperatures,  be  heated  to  88°, 
ordinarily  a  proportionally  strong  inversion  takes  place. 
This  is  the  case  with  sulphate  of  lime,  nitrate  of  potash, 
and  sulphate  of  magnesia.  Water  containing  sulphate  of 
lime  and  ammonic  chloride  shows  the  strongest  reaction  in 
consequence  of  the  formation  of  an  acid  salt.  (3)  Sugar 
solutions  mixed  with  salts  and  heated  to  88°  immediately 
after  preparation,  indicated  inversion  only  in  the  case  of 
sulphate  of  lime  and  ammonic  chloride.  (4)  The  assump- 
tion of  Bechamp  that  some  salts,  through  their  "  person- 
al" influence,  can  convert  cane-sugar  into  invert-sugar 
without  formation  of  mould,  seems  to  be  just. 

According  to  Berthelot,*  dry  cane-sugar  is  not  altered  by 
being  heated  to  100°  for  several  hours  with  NaCl,  SrCl2,  or 
BaCl2 ;  but  the  addition  of  a  small  quantity  of  water  causes 
inversion  more  abundantly  than  it  would  have  in  the  pre- 
sence of  water  alone ;  the  same  transformation  takes  place 
more  quickly  with  ammonic  chloride  and  a  little  water,  the 
mass  being  blackened.  Sodium  chloride  and  fluor-spar  do 
not  seem  to  have  the  same  effect. 

The  researches  of  Pellet,  f  upon  the  invertive  action  of 
glucose  and  salts,  made  under  different  conditions  as  re- 
gards time  and  temperature,  give  the  following  results :  As 
regards  time,  glucose  forms  quicker  the  more  dilute  the 
solutions  ;  heat  increases  the  quantity  of  invert-sugar,  and 
the  action  is  stronger  in  dilute  than  in  concentrated  solu- 
tions ;  glucose  aids  the  inversion  the  more  as  the  quantity 
of  it  is  greater — the  action  is  nil  in  saturated  solutions ; 
salts — the  inorganic  salts  have  a  much  greater  action  at 
50°  to  60°  than  at  ordinary  temperatures  ;  it  is  also  greater 

*  Ann.  Chim.  Phys.,  xxxviii.  57.        \  Journ.  des  Fattricants,  xviii.  No.  10, 


MELASSIGENIC  ACTION.  67 

with  dilute  solutions ;  nitrate  of  calcium  acts  more  ener- 
getically than  the  chloride,  and  ammonic  nitrate  gives  a 
powerful  inversion.  100  c.c.  of  water,  10  grammes  of 
sugar,  and  5  grammes  of  the  ammonia  salt,  heated  half  an 
hour,  give  a  complete  transformation  of  the  sugar  into 
invert-sugar.* 

Durin  found  that  the  presence  of  invert-sugar  in  a  solu- 
tion of  cane-sugar  caused  no  inversion  at  70°  to  75°  C. 
when  the  alkalinity  is  maintained  at  .001  of  CaO  ;  on  heat- 
ing, however,  to  75°, to  114°  C.,  the  solution  becomes  faintly 
acid,  inversion  begins  and  goes  on  until  complete  change 
of  the  sugar  is  effected ;  if  the  solution  is  kept  alkaline  no 
change  takes  place.  The  presence  of  invert-sugar  is  not 
necessary,  the  change  taking  place  on  formation  of  acids,  f 

B.  Action  on  Crystallization.— The  effect  that  mine- 
ral and  organic  salts  have  on  the  crystallizing  power  of 
cane-sugar  in  aqueous  solutions  has  engaged  the  attention 
of  many  chemists,  and  the  results  obtained  by  them  differ 
in  important  particulars  both  as  to  whether  the  specific 
melassigenic  action  exists  at  all,  and  as  to  the  special  effect 
of  the  different  salts  in  this  direction.  The  work  done  upon 
the  subject  has  had  reference  principally  not  to  pure  sugar 
solutions,  but  to  the  juices  and  mola,sses  derived  from  the 
beet ;  therefore  due  regard  should  be  paid  to  this  fact  in 
the  case  of  similar  solutions  from  the  cane,  as  the  condi- 
tions are  quite  different.  Beet  and  cane  molasses  contain, 

*  Bodenbender  denies  the  completeness  of  the  change,  and  ascribes  it  to  the 
presence  of  free  acid. 

•j-  The  above  results  are  quite  in  conformity  with  the  experience  of  the  au- 
thor, who  finds  that  a  perfectly  neutral  or  slightly  alkaline  solution  of  raw 
sugar,  on  being  heated  for  some  hours,  invariably  develops  acidity  with  conse- 
quent inversion.  The  acid  is  probably  formed  by  the  decomposition  of  invert- 
sugar  or  impurities  present. 


68 


CANE-SUGAR  OR  SACCHAROSE. 


on  the  average,  when  all  the  sugar  that  will  crystallize  has 
been  obtained : 


Beet-molasses. 

Cane-molasses. 

Cane-sugar      .        ....         .... 

e  e  QO 

15  OO 

Organic  matters  not  sugar.  .  ,  .  . 
Water      

13.00 
2O  OO 

10.00 
2O  OO 

Glucose  

Trace 

^O  OO 

Ash  

12  OO 

Z  OO 

100.00 

100.00 

The  mineral  salts  in  the  two  are  very  different  in  character, 
consisting,  in  the  case  of  cane-molasses,  in  large  part  of 
lime  salts  of  organic  and  mineral  acids,  with  a  compara- 
tively small  portion  of  alkaline  salts,  which  are  mostly  chlo- 
rides and  sulphates  ;  in  beet-molasses  the  salts  are  largely 
those  of  potassium  combined  as  chloride,  sulphate,  and  ni- 
trate, or  with  organic  acids.  The  organic  matters  asso- 
ciated in  the  two  types  are  also  as  varied  in  kind,  and  the 
further  influence  of  the  large  amount  of  glucose  in  cane- 
molasses  renders  still  greater  the  essential  dissimilarity  in 
the  two  products.  Still,  to  a  certain  extent  and  with  the 
proper  allowances,  what  is  true  of  the  action  of  salts  on 
crystallization  in  the  beet-sugar  manufacture  is  also  true 
with  the  products  of  the  cane. 

It  has  been  widely  asserted  that  the  melassigenic  effect  is 
purely  molecular  and  physical.  Champion  and  Pellet,*  as 
the  result  of  an  elaborate  series  of  experiments  on  the  sub- 
ject, conclude  that  the  action  depends — 

1.  On  the  influence  of  the  active  body  on  the  solubility 
of  the  cane-sugar. 

2.  On  its  influence  upon  the  'boiling-point  of  the  solu- 
tion. 


Sucrerie  Indigene,  xii.  210,  223,  257. 


MELASSIGBNIC  ACTION. 


fcrj, 


3.  Oft  ^6  viscosity  of  the  solution. 
These  conclusions  are  supported  by  other  chemists. 

Recently  Gunning*  has  proposed  a  different  explana- 
tion, and  one  which  probably  accounts  for  the  phenomena 
to  a  great  extent.  His  views,  founded  on  experimental 
data,  are  that  the  saccharose  contained  in  molasses  (beet  ?) 
exists  for  the  most  (nine-tenths  of  total)  part  in  the  form  of 
a  chemical  combination  of  double  salts,  in  which  the  cane- 
sugar  is  combined  with  organic  compounds  containing  a 
mineral  base,  these  double  compounds  being  non-crystal- 
line ;  if  the  theory  is  correct  it  offers  an  explanation  of 
melassigenic  action  from  a  purely  chemical  point  of  view. 
Gunning  finds  that  nearly  all  organic  potash  salts  are  capa- 
ble of  combining  with  sugar,  though  this  property  is  not 
shared  by  the  sodium  salts  for  the  most  part.  The  follow- 
ing salts  may,  however,  be  excepted  :  sodium  formiate  and 
acetate,  potassium  phosphate  and  nitrate,  sodium  carbonate 
and  barium  chloride.  The  fact  that  the  sugar  in  cane-mo- 
lasses, as  shown  by  the  foregoing  analysis  (page  68),  may 
be  reduced  to  a  lower  quantity  relative  to  the  impurities,  by 
crystallization,  seems  to  support  Gunning's  views,  as  there 
is  a  comparatively  small  quantity  of  potassium  salts  in 
cane-juice  and  its  products. 

A.  Marschall  f  has  made  a  valuable  series  of  experiments 
upon  the  influence  of  salts  on  the  crystallizing  power  of 
sugar.  He  enclosed  sugar  in  a  sealed  tube  with  a  quantity 
of  various  salts,  the  amount  of  water  present  teing  less 
than  half  that  of  the  sugar,  and,  therefore,  not  enough  to 
dissolve  all  of  it  at'  ordinary  temperatures  ;  the  tubes,  after 
filling,  were  warmed  until  the  sugar  was  in  solution,  and 
then  allowed  to  rest  in  a  cool  place  from  17  to  21  days, 

*  Stammer's  Jahresb.,  xvii.  181.  f  Journ.  Chem.  Soc.t  [2]  ix.  457. 


70  CANE-SUGAR  OR  SACCHAROSE. 

when  the  sugar  crystallized  out.  The  mother-liquors  were 
then  examined,  the  sugar  and  salt  contained  being  esti- 
mated. If  the  given  salt  prevented  crystallization,  the 
solution  would  contain  a  quantity  of  sugar  less  than  the 
normal  (2  of  cane-sugar  to  1  of  water)  for  a  saturation  solu- 
tion in  the  cold.  The  results  were  thus  classified : 

(a)  NEGATIVE  MOLASSES-MAKERS,  or  bodies  which  dimi- 
nish the  solvent  power  of  water  for  cane-sugar,  are :  sodium 
sulphate,  nitrate,  acetate,  butyrate,  valerate,  and  malate ; 
magnesium  sulphate,  nitrate,  and  chloride  ;  and  calcium 
chloride  and  nitrate. 

(&)  INDIFFERENT  BODIES — without  influence  on  crystalli- 
zation, are :  potassium  sulphate,  nitrate,  chloride,  valerate, 
oxalate,  and  malate  ;  sodium  chloride,  carbonate,  oxalate, 
and  citrate,  and  caustic  lime. 

(c)  POSITIVE  MOLASSES-MAKERS  are :  potassium  carbonate 
(saline  coefficient  .38),  acetate  (.9),  butyrate  (.9),  and  citrate 
(.6).  The  action  of  the  negative  molasses -formers,  or  those 
that  actually  aid  crystallization,  is  shown  quantitatively  as 
follows : 

MgS04  causes  to  crystallize  10  times  its  weight  of  sugar. 
MgCl2       "  "          17     "  " 

Ca(]ST03)2  "  "  4  ' "  "  " 

CaCl2         "  "          7.5  " 

The  results  of  Marschall  are  at  variance  with  those  of 
other  chemists  in  regard  to  individual  salts  ;  and  though 
the  conditions  are  scarcely  such  as  obtain  in  the  sugar 
manufacture,  they  are  of  considerable  value  in  showing 
the  general  tendency  of  the  various  salts  in  this  relation. 

La  Grange,*  working  after  the  general  method  of  Mar- 

*  La  Sucrerie  Indigene,  x.  259. 


MELASSIGENIC  ACTION. 


71 


schall,  considers,  of  all  salts,  the  chlorides  to  have  the  least 
melassigenic  effect,  sodium  chloride  having  scarcely  any, 
the  sulphates  and  carbonates  coming  next,  and  the  alkaline 
nitrates  most  of  all.  The  following  table  shows  his  results 
for  several  salts  with  their  saline  coefficient,  or  the  propor- 
tion of  their  own  weight  of  sugar  they  can  render  uncrys- 
tallizable : 


Yield  in 
cane-sugar 
per  loo  K. 

Coeff. 

Yield  in 
sugar 
per  100  K. 

Coeff. 

Normal  syrup 

*4  K 

o 

K2CO3 

47  K 

3CQ 

NaCl            .... 

<u  K 

o 

KNO3     . 

41  K 

c  CQ 

KC1  

48  K. 

3  OO 

NaNO3  

41  K. 

6.c.o 

CaCl2 

m  K 

eft 

FO4Na3 

44  K 

e  OO 

Na2SO4  .. 

50  K 

2  OO 

K2SO4  

47  K. 

1  50 

Na2CO3 

47  K 

3CQ 

Champion  and  Pellet*  give  the  saline  coefficient  for  a 
mixture  of — 

(1)  2|-  grammes  potassium  nitrate  and  1^  grammes 

potassium  chloride  as .77 

(2)  Of  the  organic  bodies  separated  by  subacetate 

of  lead  and  sulphuretted  hydrogen  as 1.42 

(3)  Invert-sugar  of  the  optically  inactive  kind  oc- 

curring in  commercial  products .56 

These  results  have  reference  to  beet-juice  or  molasses. 
For  cane-molasses  the  coefficient  of  potassium 

chloride  is 9  to  1.0 

Organic  substances  separated  as  above .86 

Invert-sugar , .56 

The  authors  assume  that  potassium  chloride  is  25  per 


*  La  Sacrerie  Indigene,  xii.  210,  223,  257. 


72  CANE-SUGAR  OR  SACCHAROSE. 

cent,  of  the  total  weight  of  cane-molasses  ash,  and  that 
the  balance  has  no  melassigenic  action. 

Vivien  and  Maumene  consider  that  chlorides  in  general, 
and  especially  chloride  of  sodium,  have  no  melassigenic 
action.  See  also  Grobert  (Journ.  d.  Fabr.  Sucre,  xx.  No. 
5;  Zeit.  f.  Rubenz.,  xxix.  806). 

Various  Reactions  of  Cane-Sugar. — Oxalate,  citrate, 
carbonate,  and  basic  phosphate -of  calcium  are  less  soluble 
in  a  sugar  solution  than  in  pure  water.  According  to  Sost- 
man,  sugar- water  dissolves  calcium  sulphate  in  proportion- 
ally greater  quantity  as  the  solution  is  more  concentrated 
and  as  the  temperature  is  elevated.  The  solution,  when 
boiled,  gives  up  a  portion  of  the  salt.  According  to  Bou- 
chardat,  nascent  hydrogen  converts  cane-sugar  into  man- 
nite,  dulcite,  or  alcohols  such  as  ethylic,  isopropylic,  and 
hexylic.  Sulphydrate  of  ammonia,  heated  in  a  sealed  tube 
to  150°  with  cane-sugar,  gives  a  sulphuretted  ethereal  oil. 
Fluoride  of  boron  is  not  absorbed  by  sugar  in  the  cold,  but 
on  heating  it  is  taken  up  and  the  sugar  blackened.  Tetra- 
chloride  of  carbon  heated  to  100°  with  sugar  is  gradually 
colored  brown  and  black,  while  dextrose  is  not  altered. 
Oil  of  sesame,  mixed  with  its  volume  of  hydrochloric  acid 
of  commerce  and  raised  to  the  boiling-point  with  a  solution 
of  cane  or  invert  sugar  produces  a  rose-color,  even  if 
only  jnnhnr  part  of  the  sugar  is  present  (Vidan).  In  the 
presence  of  (Jane-sugar  a  certain  number  cf  metallic  salts 
are  not  precipitated,  or  only  imperfectly,  by  ammonia. 

Parasaccharose. — This  body,  according  to  Jodin,  is 
produced  by  the  fermentation  of  a  cane-sugar  solution  con- 
taining ammonic  phosphate,  together  with  another  sugar 
isomeric  with  dextrose.  It  has  the  same  composition  as 
cane-sugar,  crystalline,  very  soluble  in  water  and  insolu- 


INACTIVE  CANE-SUGAR.  73 

ble  in  alcohol  of  90  per  cent.  Sp.  rotatory  power,  108°, 
varying  a  little  with  fluctuations  of  temperature.  Its 
action  on  alkaline  solution  of  oxide  of  copper  is  about 
half  that  of  dextrose.  It  is  not  altered  by  heating  with 
sulphuric  acid. 

Inactive  Cane-Sugar  is  a  substance  produced  by  the 
combination  of  parasaccharose  and  levulose,  and  is 
formed  when  solutions  containing  in  certain  proportions 
cane-sugar,  phosphate  of  sodium,  and  sulphate  of  ammo- 
nium are  allowed  free  access  to  the  air.  It  is  uncrystal- 
lizable,  does  not  reduce  alkaline  copper  solution,  and  is  in- 
active to  polarized  light.  Dilute  acids  transform  it  to  a 
levo-rotatory  sugar  having  [a]  j  =  —  69,  which  reduces  cop- 
per solution  (Jodin.*). 

*  Bull  Soc.  Chim.,  i.  366. 


CHAPTER  III. 

Dextrose,  Levulose,  and  Invert-Sugar. 
DEXTEOSE  C6H12O6. 

Glucose— Grape- Sugar— RigJit-Tianded  Sugar— Sucre  de 
Rasin^  Fr. — Krumelzucker,  TraubenzucTcer,  Gr. ; 
and,  according  to  its  origin — Fruit-Sugar — Honey- 
Sugar — Starch-Sugar — Diabetic  /Sugar — Hag-Sugar — 
HarnzucJter,  Gr. 

DEXTEOSE  was  first  noticed  by  Lowitz  and  Proust,  pre- 
pared from  starch  by  Kirckhoff,  and  from  linen  by  Bra- 
connot.  Its  combinations  with  bases  have  been  chiefly 
Studied  by  Peligot,*  and  with  organic  acids  by  Berthelot.f 
Dubrunf  aut  has  also  added  much  to  our  knowledge  of  the 
chemical  history  of  dextrose.^ 

Dextrose  occurs  widely  distributed  in  the  vegetable 
kingdom  in  sweet  fruits  and  grape-juice,  associated  often 
with  cane-sugar  and  levulose ;  with  the  latter  often  in 
such  a  proportion  as  to  constitute  invert-sugar.  It  is  also 
found  in  honey  and  numerous  cereals.  Many  animal  liquids 
and  tissues  contain  dextrose,  as  the  liver,  blood,  chyle,  the 
yolk  and  white  of  eggs.  Diabetic  urine  often  holds  dex- 
trose to  the  amount  of  eight  to  ten  per  cent.,  as  does  the 
healthy  secretion  in  small  quantity  (Bence  Jones). 

*  Ann.  Chim.  PTiys.,  [2]  Ixvii.  136.        f  Ibid.,  [3]  liv.  74 ;  Ix.  95. 
\Ibid.,  [3]  liii.  73  ;  xxi.  169,  178;   Compt.  Rend.,  xxiii.  38;  xxv.  308;   xxix. 
51;xxxii.249;  xlii.  228,  739. 

74 


FORMATION  OF  DEXTROSE.  75 

Formation.  —  By  the  transformation  of  carbohydrates 
with  the  assumption  of  water  —  as 

3C.H1006  +  H20  =  C6H1306  +  2C6HI006. 

Starch.  Dextrose.          Dextrin. 

The  above  change  takes  place  when  starch  is  boiled  with 
dilute  acids.  If  the  acid  is  allowed  to  act  for  some  time, 
the  dextrin  first  formed  is  converted  into  dextrose.  Starch 
is  also  converted  into  dextrose  by  long  boiling  with  water, 
and  continued  contact  with  gluten,  saliva,  and  nitrogenous 
matters. 

Glycogen  and  lichenin  are  changed  to  dextrose  by  boil- 
ing with  dilute  acids.  When  cellulose  is  treated  with  oil 
of  vitriol,  strong  hydrochloric  acid,  or  concentrated  so- 
lution of  zinc  chloride,  diluted,  and  the  solution  thus  ob- 
tained boiled,  dextrose  is  formed.  Tunicin,  under  the 
same  circumstances,  is  converted  into  dextrose.  Maltose, 
melezitose,  trehalose,  and  mycose  give  rise  to  dextrose  by 
boiling  with  dilute  acids. 

Kosman  *  has  found  that  grape-sugar  or  dextrose  may 
be  formed  from  glycerin  and  cellulose  in  the  presence  of 
air,  water,  and  metallic  iron,  according  to  the  reaction: 

2C3H803  +  03  =  C6H1206  +  2HaO. 

Grlucosides,  by  boiling  with  dilute  acids,  produce  dextrose 
and  a  non-saccharine  body,  by  assumption  of  water.  The 
transformation  may  be  illustrated  by  one  case: 


+  2HaO  -  2C6H1206  +  C7H6O  +  CHK 

Amygdalin.  Dextrose.  Bitter-        Hydrocyanic 

almond  oil.         acid. 

Preparation.  —  FROM  STARCH  BY  THE  ACTION  OF  DI- 
LUTE ACIDS.  —  One  part  of  starch  is  boiled  with  four  parts 

*  Bull.  Soc.  Chirn.,  xxviii.  246. 


76  DEXTROSE,  LEVULOSE,  AND  INVERT-SUGAR. 

• 

of  water,  and  oil  of  vitriol  in  the  quantity  of  TV  to  yj-g-  of 
the  starch,  the  mixture  stirred  and  kept  at  its  original 
volume  by  the  addition  of  water,  until  it  is  no  longer  pre- 
cipitated by  alcohol.  From  six  to  thirty-six  hours  of 
boiling  are  required,  according  to  the  amount  of  sulphuric 
acid  present.  The  free  acid  is  then  neutralized  by  chalk, 
the  liquid  evaporated  to  20°  B.,  allowed  to  stand  to  deposit 
impurities,  or  is  clarified,  if  necessary,  with  white  of  egg, 
filtered  through  animal  charcoal,  and  the  filtrate  evapo- 
rated to  a  thick  syrup  from  which  the  sugar  separates 
after  a  few  weeks.  This  product  should  be  recrystallized. 

PREPARATION  OF  PURE  DEXTROSE  (F.  Soxhlet*). — One 
kilogramme  of  refined  white  cane-sugar  is  mixed  with 
three  litres  of  90  per  cent,  alcohol  and  120  c.c.  pure,  strong 
hydrochloric  acid,  and  heated  at  45°  C.  for  two  hours  to 
invert.  After  ten  days'  standing  crystals  of  dextrose  be- 
gin to  form,  and  in  thirty-six  hours  dextrose  is  largely 
thrown  down  in  crystals  and  powder.  The  deposit  is 
washed  with  90  per  cent,  and  absolute  alcohol,  being  final- 
ly recrystallized  from  the  purest  methylic  alcohol  (.810  sp. 
gr.  for  a  quick  crystallization,  and  .820  sp.  gr.  for  a  slower 
one). 

PREPARATION  FROM  DIABETIC  URINE. — Add  excess  of 
sodium  chloride,  when  the  glucosate  is  formed,  which 
easily  crystallizes  out  from  a  concentrated  solution.  The 
crystals  are  purified  by  washing  with  a  saturated  solution 
of  salt,  and  finally  with  alcohol.  The  purified  crystals  are 
then  dissolved  in  water,  treated  with  sulphate  of  silver, 
filtered,  and  the  mixture  of  dextrose  and  sodium  sulphate 
evaporated  to  dryness  on  a  water-bath.  Strong  alcohol 

*  See  also  Schwarz,  Dingier,  ccv.  427 ;  Muspratt-Kerl,  Ilandbuch,  vi.  2078 ; 
Neubauer,  Zeit.  Rubenz.,  1876,  782. 


PROPERTIES  OF  DEXTROSE.  77 

dissolves  out  the  pure  dextrose  from  the  residue,  leaving 
the  sulphate. 

Properties. — From  alcohol  of  95  per  cent,  anhydrous 
dextrose  is  deposited  in  microscopic,  well-defined  needles, 
which  melt  at  146°  C.  to  a  colorless,  transparent  mass. 
Anhydrous  dextrose  is  obtained  as  a  white  powder  by 
heating  hydrated  dextrose  to  60°  C.  in  a  stream  of  air. 
Crystallized  dextrose  dissolves  at  first  quickly  in  water, 
but  as  the  solution  becomes  more  concentrated  the  action 
becomes  much  slower,  so  that  several  days  are  necessary 
for  water  to  take  up  the  full  amount  it  is  capable  of  dis- 
solving. The  concentrated  syrup  has  not  the  elasticity  or 
ropiness  of  cane-sugar  syrup,  and  is  disposed  to  be  stringy 
when  drawn  out.  100  parts  of  water  at  15°  C.  dissolve 
81.68  parts  of  anhydrous  dextrose  and  97.85  parts  of  hy- 
drated dextrose.  The  saturated  solution  contains  44.96 
per  cent,  anhydrous  dextrose  ;  sp.  gr.  1.206.  According  to 
Anthon,  by  dissolving  hard  crystallized  dextrose  in  warm 
water  a  solution  of  density  1.221  at  17^°  may  be  obtained. 
Dextrose  seems  to  dissolve  more  readily  when  foreign  mat- 
ters are  present.  The  sp.  gr.  of  dextrose  solution  differs 
somewhat  from  that  of  cane-sugar  containing  the  same 
amount  of  substance.  The  following  table  is  given  by 
Pohl*: 

*  Wien.  Akad.  Ber.,  ii,  664. 


78 


DEXTROSE,  LEVULOSE,  AND  INVERT-SUGAR. 


Density  of  solution. 

Difference  in 

T>           y*     «•»« 

JT  cr  cent*  sugar* 

Cane-  Sugar. 

Grape-  Sugar. 

2 

1.0080 

1.0072 

—    8 

5 

I.O2OI 

I.O2OO 

—     I 

7 

I.028I 

1.0275 

—    6 

10 

1.0405 

1.0406 

+     i 

12 

1.0487 

1.0480 

—    7 

15 

I.  O6l6 

I.  O6l6 

+    o 

17 

1.0704 

1.0693 

—  ii 

20 

1.0838 

1.0831      , 

—    7 

22 

1.0929 

1.0909 

—  20 

25 

I.I068 

I.IO2I 

—  47 

Dextrose  is  soluble  in  aqueous  alcohol  in  varying  propor- 
tions,  less  easily,   however,   than  cane-sugar.      Anthon* 
gives  the  following  solubilities :  1  part  of  dextrose  requires 
for  solution    50      parts  alcohol  of  .837  sp.  gr. 
11.37      "          "        ".  .880      " 
.6.21      "          "        "   .910      " 
2.07      "          "        "   .950      " 

Melted  dextrose  deliquesces,  and  then  solidifies  to  a 
crystalline  hydrate.  On  evaporation  of  a  solution  the 
thick  syrup  does  not  solidify  until  sufficient  water  is  ab- 
sorbed to  form  a  hydrate.  Crystals  separating  from  an  al- 
coholic solution  are  hydrous  or  anhydrous,  according  to 
the  strength  of  the  alcohol ;  insoluble  in  ether. 

Specific  Rotatory  Power.— -For  the  anhydrous  [a]  j  = 
52.5°,  Clerget ;  53.2°,  Dubrunfaut ;  55.1°,  Pasteur ;  56°,  Ber- 
thelot ;  57°,  Schmidt ;  57.4°,  Bechamp  ;  57.7°,  Jodin.  Tol- 
lens,  as  the  result  of  later  investigations^  gives  the  follow- 
ing general  formulas : 

'  For  the  hydrate  when  the  solution  contains  8  to  91  per 
cent,  of  active  substance : 


*  Dingier,  Polyt.  Journal,  civ.  386. 


\Ber.  Chem.  Gesell,  ix.  1531. 


SPECIFIC  ROTATORY  POWER. 


79 


[a]D  =  47.925  +  .015534^  +  .  0003883  p* ; 
for  the  anhydrous  p  —  7  to  83. 

[a]  D  =  52.718  +  .017087^  +  .0004271  p* : 

p  =  the  percentage  of  sugar  dissolved. 

Hoppe-Seyler  *  has  obtained  for  dextrose  extracted  from 
urine  a  value  of 

[a]  D  =  56.4°  (anhydrous);  c  =  14  to  29  grm. 

See  also  Hesse,  f 

A  freshly-prepared  solution  of  hydrated  dextrose,  or  de- 
hydrated dextrose  prepared  without  fusion,  shows  a  rota- 
tory power  equal  to  nearly  twice  the  above,  but  which 
gradually  sinks  to  the  normal,  and  then  remains  constant ; 
by  heating,  the  excessive  rotation  may  be  destroyed  at 
once.  Dubrunfaut  has  called  the  sugar  having  this  pro- 
perty Mrotatory  dextrose;  and  the  phenomenon  itself, 
birotation. 

Composition. — 


Centesimally. 

In  equivalents. 

40.00 

72 

6.67 

12 

Oxygen                               . 

e-i  0-7 

06 

100.00 

1  80 

Decompositions — Heat. — When  dextrose  dried  at  100° 
C.  is  heated  to  170°  C.,  it  gives  off  two  molecules  of  water 
and  is  converted  into  glucosan  (Grelis^:) ;  at  210°  C.  to  220° 
C.  it  swells,  gives  off  more  water,  and  yields  caramel.     The 
products  formed  at  a  high  temperature  are  similar  to  those 


*  Fres.  Zeitsclirift,  xiv.  305. 
f  Ann.  der  Chem.,  clxxvi.  102. 


Compt.  Rend.,  li.  331. 


80  DEXTROSE,  LEVULOSE,  AND  INVERT-SUGAR. 

obtained  from  cane-sugar  under  the  same  circumstances, 
but  are  somewhat  more  fusible,  more  easily  soluble  in 
water,  and  less  soluble  in  alcohol.  The  products  of  the 
electrolytic  decomposition  of  dextrose  are  hydrogen,  oxy- 
gen, carbonic  oxide,  carbonic  acid,  the  solution  containing 
acetic  and  formic  acids,  and  aldehyde. 

When  heated  with  chromic  acid,  we  peroxide  of  manga- 
nese and  sulphuric  acid,  formic  acid  is  produced.  Potas- 
sium dichromate  warmed  with  aqueous  dextrose  does  not 
alter  it,  but  the  presence  of  the  latter  prevents  the  reaction 
with  cane-sugar.  Nascent  liydrogen  converts  dextrose  into 
mannite.  Fuming  nitric  acid  forms  nitro-dextrose  ;  with 
ordinary  or  moderately  dilute  acid  in  the  heat,  saccharic 
and  oxalic  acids  are  formed,  but  no  tartaric  acid.  Warmed 
with  one  molecule  of  acid  carbonate  of  potassium  and  one 
of  iodine,  iodof  orm  is  produced  (Millon).  Bromine  heated 
in  a  seale4  tube  with  dextrose  yields  hydrobromic  acid  and 
a  humus-like  product ;  clilorine  has  a  similar  action.  Bi- 
chloride of  tin  acts  in  the  same  manner  as  upon  cane-sugar. 

Cold  concentrated  sulpliuric  acid,  when  triturated  with 
dextrose,  dissolves  it  without  coloration,  forming  a  conju- 
gated compound :  glucoso-sutpliuric  acid  C24H48S027.  On 
heating  charring  takes  place.  Boiled  with  dilute  acids, 
ulmin  and  ulmic  acid  are  formed.  According  to  Gautier,* 
when  gaseous  hydrochloric  acid  is  passed  into  a  cooled 
alcoholic  solution  of  dextrose,  an  isomer  of  cane-sugar  is 
formed  having  a  bitter  taste,  soluble  in  water  and  alcohol, 
and  which  reduces  cupric  oxide  in  alkaline  solution. 

Action  of  Alkalies. — Gaseous  ammonia  is  readily  ab- 
sorbed by  dextrose  when  heated  to  100°  to  110°,  water  con- 
taining ammonic  carbonate  distilling  off  and  a  nitrogenous 

*  Ber.  Chem.  GeselL,  vii.  1549. 


VARIOUS  REACTIONS.  81 

residue  being  left.  Dextrose  is  decomposed  by  long  con- 
tact with  alkalies,  alkaline  earths,  and  some  metallic 
oxides,  forming  glucic  acid  (Peligot)  ;  when  heated  with 
potash  lye,  the  mixture  becomes  dark  brown,  smells  of 
caramel,  and  contains  glucic  acid  C12H18O9  and  melassic 
acid  C12H10O5.  E.  Feltz  *  gives  the  products  of  decomposi- 
tion by  heating  with  caustic  alkalies,  as  saccharic,  glucic, 
and  apoglucic  acids,  of  which  the  first  two  reduce  the  oxide 
of  copper  in  alkaline  solution  in  small  quantity.  Alkaline 
carbonates  and  aqueous  ammonia  produce  the  same  effect 
as  potash  lye. 

Lime  distilled  with  a  thick  syrup  of  dextrose  yields  an 
oil  from  which  pTiorone  and  metacetone  may  be  obtained. 
Baryta-water  boiled  with  dextrose,  out  of  contact  with  the 
air,  furnishes  a  solution  which  at  first  is  yellow,  but  be- 
comes dark  on  ebullition,  and  then  contains  glucate  of 
baryta  and  another  baryta  salt  from  which  aceto-formic 
acid  C3H4O3  2H2O  may  be  obtained  by  distillation  with 
dilute  sulphuric  acid. 

Various  Reactions. — Solution  of  carbonate  of  soda 
heated  with  dextrose  and  basic  nitrate  of  bismuth  produces 
a  black-brown  liquid  and  a  grayish-brown  precipitate ;  f 
this  may  serve  as  a  qualitative  reaction  in  the  presence  of 
cane-sugar  and  in  urine.  Oxide  of  lead  heated  to  110°  with 
dextrose  converts  it  into  melassic  acid  in  whole  or  part. 
Ferric  sulphate  and  chloride  are  reduced  to  the  ferrous 
salts  on  boiling  with  aqueous  dextrose.  Mixed  with  ni- 
trate of  cobalt  and  a  small  quantity  of  fused  caustic  potash, 
the  solution  remains  clear  on  boiling,  or,  if  very  concen- 
trated, deposits  a  light-brown  precipitate  ;  the  presence  of 

*  Sucrerie  Indigene,  vii.  165.         f  Boettger,  Journ.  Pk.  Chemie,  li.  431. 


82  DEXTROSE,  LEVULOSE,  AND  INVERT-SUGAR. 

glucose  prevents  the  appearance  of  the  violet-blue  preci- 
pitate with  cane-sugar  in  this  reaction, 

When  cupric  sulphate  in  solution  is  mixed  with  aqueous 
dextrose  and  potash  lye,  the  cupric  hydrate,  which  at  first 
separates,  dissolves  with  a  deep  blue  color,  and  deposits 
cuprous  oxide  after  some  time  in  the  cold,  and  immediately 
when  heated ;  this  reaction  is  sensitive  to  detect  and  dis- 
tinguish 1-100000  part  of  dextrose  in  the  presence  of  cane- 
sugar,  starch,  or  gum ;  under  favorable  circumstances,  by 
the  reddish  color  which  the  liquid  assumes  without  preci- 
pitation, 1-1000000  part  of  dextrose  may  be  shown  (Trom- 
mer*);  compare  Guibourt.f  Carbonic  acid  is  formed  in 
this  reaction,  as  is  also  formic  when  cane-sugar  is  in  excess, 
together  with  a  peculiar  body,  resembling  humic  acid, 
which  remains  in  combination  with  the  alkali. 

If  dextrose  is  mixed  with  indigo  solution,  and  the  liquid 
boiled,  carbonate  of  sodium  solution  being  dropped  in  at 
the  same  time,  the  liquid  is  decolorized  by  the  reduction  of 
the  indigo.  ^  Nitrate  of  silver  boiled  with  dextrose  throws 
down  metallic  silver  as  a  black  precipitate.  An  aqueous 
solution  of  one  ^zxiferricyanide  of  potassium,  mixed  with 
a  half  part  of  caustic  potash  and  heated  to  60°  to  80°,  is 
decolorized  when  dextrose  is  added ;  invert-sugar  behaves 
in  the  same  way,  but  cane-sugar  and  dextrin  prepared  by 
roasting  do  not  (see  page  210).  If  oil  of  vitriol  is  gradu- 
ally added  to  an  aqueous  solution  of  ox-gall,  until  the  pre- 
cipitate first  formed  is  redissolved,  the  liquid  assumes  a 
violet-red  color,  similar  to  that  of  potassium  permanganate, 
on  the  addition  of  cane-sugar,  dextrose,  or  starch  (Petten- 
kofer) ;  according  to  Van  Brock,  the  extractive  matter  of 

*  Ann.  Pharm.,  xxxix.  361.  f  Neues  Journ.  Pharm.,  xii.  263. 

t  Mulder.  Neubauer,  Zeit.  /.  Anal.  Chemie,  i.  377. 


COMBINATIONS.  83 

healthy  urine  and  the  reagents  themselves  produce  this  colo- 
ration in  the  absence  of  sugar.  Dextrose  absorbs  oxygen 
readily,  and  reduces  the  salts  of  gold,  silver,  and  bismuth 
to  the  metal,  being  oxidized  to  formic,  oxalic,  and  tar- 
tronic  acids  and  aldehyde  (page  185). 

COMBINATIONS. 

With  Water. — Dextrose  forms  two  hydrates  : 

(a)  HEMI-HYDRATED  DEXTROSE^  2C6H1206  H2O  (Anthon's 
hard  crystallized  glucose).  Prepared  by  a  secret  process.* 

(&)  MONO-HYDRATED  DEXTROSE  C6H12O6  H2O.  Obtained 
in  white,  granular,  hemispherical  or  cauliflower  shaped 
masses  with  occasional  shining  faces.  It  loses  some  water 
at  65°-70°,  and  in  a  vacuum  at  90°-100°  it  becomes  anhy-' 
drous. 

With  Bases. — Alkalies,  aUcaline  earths,  and  plumbic 
oxide  form  compounds  with  dextrose  which  are  more  easily 
decomposed  than  similar  compounds  of  cane-sugar.  Aque- 
ous dextrose  takes  up  a  large  quantity  of  the  oxides  of 
'barium,  calcium,  and  strontium,  forming  yellow  solutions 
precipitated  by  alcohol,  which,  even  when  protected  from 
the  air,  become  darker,  and  are  decomposed  by  standing  or 
when  exposed  to  heat ;  their  taste  is  bitter  and  slightly  al- 
kaline ;  when  evaporated  in  vacuo,  a  transparent,  brittle 
mass  remains  containing  unaltered  dextrose. 

With  Potassium  and  Sodium  Oxides.— Soluble  in 
hot  alcohol,  the  former  crystallizable.  According  to  Honig 
and  Kosenfeld,  on  adding  sodium  ethylate  to  an  alcoholic 
solution  of  dextrose,  the  compound  C6HnN&O6  is  precipi- 
tated in  white  flocks,  f 

*  Chem.  Centblatt,  1859,  289.          f  Dingier' s  Journal,  ccxxxvii.  146,  153. 


84  DEXTROSE,  LEVULOSE,  AND  INVERT-SUGAR. 

With  Barium  Oxide. — (a)  Obtained  by  precipitating  a 
solution  of  dextrose  in  wood-spirit  with,  baryta  dissolved 
in  aqueous  wood-spirit ;  the  precipitate  is  washed  with 
the  latter  and  dried  in  vacuo  (Peligot).  (b)  Produced  by 
adding  alcoholic  barium  hydrate  to  excess  of  dextrose  dis- 
solved in  alcohol,  washing  the  precipitate  with  strong  alco- 
hol, and  drying  in  vacua.  It  is  a  nearly  white,  loose 
powder  of  caustic  taste,  and  is  easily  soluble  in  water. 

With  Lime.*    C.HIOCaO6  +  Aq  (Peligot), 

2(C6H12O6)CaO(H20)3  (Maumene). 

Prepared  by  adding  alcohol  to  a  freshly- made  mixture  of 
the  sugar  with  calcic  hydrate.  Insoluble  precipitate,  diffi- 
cult to  dry. 

With  Plumbic  Oxide.— Aqueous  dextrose  in  the  cold 
dissolves  plumbic  oxide,  forming  an  insoluble  basic  com- 
pound which  decomposes  even .  below  100°.  Aqueous  dex- 
trose gives  no  precipitate  with  neutral  or  basic  acetate  of 
lead,  but  gives  one  with  the  ammoniacal  acetate. 

(a)  C6H8Pb206. 

(b)  C12H22On  3PbO. 

With  Cupric  Oxide.— Salkowski  f  describes  a  com- 
pound of  cupric  oxide  which  is  formed  as  an  insoluble  pre- 
cipitate, drying  in  the  air  to  a  blue-green  powder  partly 
soluble  in  alkali. 

With  Sodium  Chloride.— The  rotatory  power  of  dex- 
trose is  not  altered  in  the  presence  of  sodium  chloride. 

(a)  C6H12O6  2NaCl  (nearly).     Obtained  by    evaporating 
sodium  chloride  with  diabetic  urine  (Staedeler). 

(b)  2C6H1206  £NaCl  H2O.     Also  obtained  by  evaporating 
diabetic  urine  with  sodium  chloride. 

*  Ann.  CMm.  Pharm.,  Ixxxiii.  138.         f  Zeits.  /.  Anal.  Chemie,  xii.  98. 


COMPOUNDS  WITH  SALTS.  85 

(c)  2C6H12O6  NaCl  H2O.  This  is  most  well-defined  of  all 
the  compounds  of  sodium  chloride  with  dextrose.  It  crys- 
tallizes out  when  diabetic  urine  is  concentrated  ;  also  from 
solutions  containing  one  molecule  or  less  of  the  salt  to  two 
molecules  of  the  sugar.  Dextrose  from  urine  forms  this 
body  more  easily  than  that  from  any  other  source.  It  con- 
sists of  transparent,  colorless,  lustrous  crystals,  attaining  a 
ha] f -inch  in  length,  belonging,  according  to  Pasteur,  to  the 
right  prismatic  or  rhombic  system.  Rotatory  power 
[a]  j  =  47.14°,  corresponding  to  the  unaltered  rotation  of 
the  dextrose  contained  (Pasteur);  permanent  in  the  air; 
loses  water  when  heated. 

With  Sodium  Bromide.*  HaBr  2(C.H190.)- 

With  Sodium  Iodide. — A  very  unstable  compound. 

With  Organic  Acids.— Dextrose  combines  with  the  or- 
ganic acids  tartaric,  stearic,  benzoic,  butyric,  and  acetic, 
forming  amorphous  solid  or  oily  masses,  soluble  in  alcohol 
and  ether,  but  slightly  soluble  in  water,  f 

Borax  behaves  with  dextrose  similarly  to  what  it 
does  with  cane-sugar.  By  the  action  of  chloracetyl  on 
dextrose  there  is  produced  a  body  having  the  composition 
C6H7(C2H30)4O6C1.  It  has  a  specific  rotatory  power  of  140°, 
reduces  cupric  oxide  in  alkaline  solution,  and  is  partially 
volatile.  Dextrose  prevents  the  precipitation  of  ferric 
chloride  by  alkalies. 

ADDITIONAL  QUALITATIVE  TESTS  FOE  DEXTEOSE. 

Barfoed's  Test. — Heat  the  solution  with  a  neutral  or 
acid  solution  of  cupric  acetate,  when  a  precipitate  is  pro- 

*  Stenhouse  (Chem.  Centb.,  1864,  64). 

f  Berthelot  (JaTiresb.  der  Chem.,  1855, 157,  507,  678). 


86  DEXTROSE,  LEVULOSE,  AND  INVERT-SUGAR. 

duced.  Dextrin,  milk,  or  cane-sugar  do  not  act.  .01  per 
cent,  may  be  thus  detected.* 

Sclmiitt's  Test. — A  solution  containing  dextrose  mixed 
with,  neutral  acetate  of  lead  and  ammonia,  gives  a  whitish 
cloud,  which  on  warming  settles  to  a  red  precipitate  of 
lead  sucrate.  Cane-sugar,  under  the  same  conditions,  gives 
a  white  precipitate  only.  A  small  trace  of  dextrose  in  the 
presence  of  much  cane-sugar  colors  the  deposit.  Mannite 
acts  as  cane-sugar. 

Mazzara's  Test. — Hydrated  sesquioxide  of  nickel, 
when  heated  with  dextrose,  in  vert- sugar,  and  many  other 
organic  bodies  in  the  presence  of  caustic  potash,  is  reduced 
to  the  green  protoxide. f  See  also  E.  Pollacci.J 

Picric  Acid  Test  (Braun  §). — Dextrose  reduces  picric 
acid  C6H3(NO2)3O  to  picraminic  acid  C6H3(NO2)JNTH20,  the 
yellow  color  changing  to  a  deep  red.  To  execute  the  test 
the  grape-sugar  solution  is  heated  with  excess  of  caustic 
soda  to  90°  C.,  and  one  or  two  drops  of  a  solution  of  picric 
acid  added  (containing  1  part  acid  to  250  parts  water),  and 
the  whole  heated  to  boiling. 

Lindo's  Test.[ — When  the  yellow  crystalline  compound 
obtained  by  the  action  of  nitric  acid  on  brucine  is  ren- 
dered alkaline  by  caustic  alkali  solution,  and  dextrose  is 
added,  the  yellow  color  changes  to  an  intense  blue. 

PARADEXTROSE. — This  substance  is  produced  with  para- 
saccharose  by  spontaneous  fermentation  of  a  cane-sugar 
solution  (see  page  72).  It  is  isomeric  with  dextrose, 
forming  a  hydrate  with  one  molecule  of  water.  It  loses 
its  water  at  100°  and  decomposes.  Paradextrose  does  not 

*  Fres,  Zeitschrift,  xii.  27.  §  Fres.  Zeitschrift,  iv.  187. 

t  Gazzetta  Chim.  Ital.,  1878,  ii.  and  iii.          ||  Chem.  News,  xxxviii.  145. 
$  Ibid. 


LEVULOSE.  87 

reduce  alkaline  solution  of  tartrate  of  copper  so  strongly 
as  dextrose,  but  by  boiling  with  dilute  acids  its  reducing 
power  is  increased.  Sp.  rotatory  power,  about  +  40°. 

LEVULOSE*  C6H12O6. 

Honigzucker,    Liriksfruclitzucker,    ScJileimzucJcer,    Gr. — 
CJiylariose,  FT. — Fruit-Sugar — Left-handed  Glucose. 

Levulose  exists  in  the  invert-sugar  of  honey  and  many 
fruits,  though  its  isolated  occurrence  has  not  been  demon- 
strated with  certainty.  Some  fruits  furnish  a  left  rotatory 
juice,  which  renders  it  probable  that  levulose  often  exists 
in  fruits  in  greater  proportion  than  that  necessary  to  form 
invert-sugar.  The  total  sugar  in  such  cases  doubtless  con- 
sists of  a  mixture  of  cane-sugar,  dextrose,  and  levulose,  or 
dextrose  and  levulose,  the  latter  always  predominating. 

Formation. — (1)  In  the  inversion  of  cane-sugar  by  wa- 
ter, dilute  acids,  yeast,  or  a  peculiar  ferment  present  in 
fruits  ;  (2)  by  boiling  levolusan  with  water  or  dilute  acids. 
The  sugar  produced  by  the  continued  heating  of  inulin 
with  acids  is  levulose,  according  to  Dubrunfaut. 

Preparation. — Add  a  little  hydrochloric  acid  to  a  solu- 
tion of  cane-sugar,  and  heat  to  60°  C.  When  about  twelve 
per  cent,  of  invert-sugar  is  present,  cool  to  —  5°  C.  and  add 
iflilk  of  lime,  when  the  temperature  will  rise  to  2°  C.  Sub- 
mit the  mixture  to  pressure  to  eliminate  the  liquid  lime 
compound  of  dextrose,  and  to  the  levulosate  of  lime  re- 
maining add  some  water,  and  again  express.  Repeat  this 
operation  until  the  liquid  running  off  has  no  longer  a 

*  Bouchardat,  Compt.  Rend.,  xxv.  274  ;  Dubrunfaut  and  others,  ibid.,  xxix. 
51,  xl.  201,  xlii.  803;  Ann.  Chim.  Phys.,  [3]  xxi.  169;  Journ.  Pk.  Chem.,  Ixix. 
438,  208,  xlii.  418. 


88      DEXTROSE,  LEVULOSE,  AND  INVERT-SUGAR. 

dextro-rotation.  The  lime  compound  is  then  decomposed 
with  oxalic  acid.  Finally,  the  solution  of  the  pure  levu- 
lose  is  submitted  to  cold  by  means  of  snow  and  hydro- 
chloric acid,  whereby  the  water  freezes  out,  and  the  syrupy 
levulose  remaining  is  further  dried  in  a  vacuum  (Girard). 
Properties. — Levulose  is  a  colorless,  uncrystallizable 
syrup  or  an  amorphous  mass.  After  heating  to  100°  its 
composition  corresponds  to  the  formula  C6H1206.  It  is 
rather  sweeter  than  cane-sugar,  and  is  purgative.  Optical 
rotatory  power  varying  with  the  temperature,  and  much 
affected  by  presence  of  caustic  lime. 

[a]j  =  -     53°     at90°C. 

-  79.5°  at  52°  C. 

-  106°     at  14°  C. 

(Dubrunfaut). 
Neubauer  makes  the  rotation  at  14°  to  be  —  100°. 

Decompositions. — Levulose,  on  being  heated  to  170° 
C.,  yields  a  product  analogous  to  glucosan,  but  more  easi- 
ly decomposed — probably  levolusan  C6H10O5  (page  79). 
In  contact  with  yeast  it  undergoes  vinous  fermentation 
without  previous  change.  When  sodium  amalgam  is 
added  to  an  aqueous  solution  of  invert-sugar,  evolution  of 
hydrogen  ceases  as  soon  as  the  liquid  has  become  alkaline, 
heat  is  given  off,  and  when  the  action  is  complete  the  solu- 
tion is  found  to  contain  mannite  (Linneman*).  Levulose 
heated  with  dilute  sulphuric  acid  forms  levulinic  acid 
(Grote  and  Tollens)  ;  it  reduces  cupric  oxide  in  alkaline 
solution  in  the  same  proportion  as  dextrose.  Chlorine, 
according  to  Hlasiwetz  and  Haberman,f  with  silver  oxide, 
acting  on  levulose,  forms  not  gluconic  but  gly collie  acid. 

*  Ann.  Pharm.,  cxxiii.  136;  Ber.  Chcm.  Gesell.,  ix.  1465;  Ann.  Chim. 
Phys.,  [5]  x.  559.  f  Her.  Chem.  Gesell,  iii.  486. 


INVERT-SUGAR.  89 

The  products  of  the  action  of  alkalies  on  levulose  are 
the  same  as  those  obtained  in  the  case  of  dextrose.  They 
are  the  more  complex  in  proportion  as  the  air  has  access.* 
The  decompositions  and  reactions  of  levulose  in  general 
are  much  the  same  as  those  of  dextrose. 

Combination  with  Lime. — Levulose  forms  with  lime 
a  basic  compound  analogous  to  that  of  dextrose,  which  ab- 
sorbs oxygen  from  the  air  and  decomposes.  Another  com- 
pound, consisting  of  sparingly  soluble  microscopic  needles, 
containing  three  molecules  of  base  to  one  of  sugar,  is 
decomposed  by  water  when  exposed  to  the  light  and  air 
(Dubrunfautf).  Peligot  gives  the  formula  C6H7O73CaO. 
Levulose  is  more  soluble  in  alcohol  than  dextrose.  A 
combination  of  sodium  with  levulose  appears  to  exist,  ac- 
cording to  Honig  and  Rosenfeld,J  of  the  formula 
C6HuNaO.. 

INVERT-SUGAR. 

This  is  a  mixture  in  equal  equivalents  of  dextrose  and 
levulose,  produced  by  the  action  of  heat,  diastase,  acids, 
salts,  or  other  agents  on  cane-sugar  and  some  of  its  iso- 
mers.  It  is  an  uncrystallizable  syrup  of  sweeter  taste 
than  cane-sugar.  The  sp.  rotatory  power  varies  with  the 
temperature  :  [a]]  = 

at     14°  52°  90° 

-  26. 65°         -  13. 33°  0°  (Dubrunf aut  §). 

According  to  Tuchscmid,|  87.2°  is  the  temperature  of  in- 

*  Peligot,  Compt.  Rend.,  No.  4,  1880.          §  Compt.  Rend.,  xlii.  901. 

f  Ibid.,  Ixix.  1366.  ||  Journ.  PL  Cfiemie,  [2]  ii.  235. 

\  Ber.  Chem.  (resell.,  xii.  45. 


90 


DEXTROSE,  LEVULOSE,  AND  INVERT-SUGAR. 


activity.  The  latter  gives  the  general  formula  when  c  — 
17.2  grm.  in  100  c.c.,  as  [a]D,  =  —  (27.9  —  .32£),  when  t  — 
the  temperature.  Alcohol  lessens  the  left  rotation  of 
invert-sugar,  especially  in  the  heat.*  Probably  the  invert- 
sugar  in  most  commercial  saccharine  products  is  optically 
inactive  at  any  temperature  (page  173).  In  the  inversion  of 
cane-sugar  by  acids,  for  every  100°  of  the  original  dextro- 
rotation  there  is  produced  an  inverse  rotation  of  —  38°  at 
15°  C.,  and  -  44°  at  0°  C. 

Chancel  f  finds  that  a  contraction  in  volume  takes  place 
when  a  solution  of  cane-sugar  is  inverted,  and  hence  invert- 
sugar  solutions  of  the  same  percentage  are  heavier  than 
those  of  cane-sugar. 

COMPARATIVE  DENSITIES  OF  CANE' AND  INVERT  SUGAR  SOLUTIONS. 


Density. 

Density. 

Per  cent,  of 

Per  cent,  of 

sugar. 

sugar. 

Cane-sugar. 

Invert-sugar. 

Cane-sugar. 

Invert-sugar. 

2 

I.OOSo 

.0082 

15 

1.0630 

1.0634 

5 

1.0203 

.O2O6 

I7M 

1.0718 

1.0722 

7 

1.0286 

.0290 

20 

1.0854 

1.0856 

10 

1.0413 

.0417 

22 

1.0946 

1.0947 

12 

1.0499 

.0503 

25 

I.I086 

I.I086 

General  references  on  invert-sugar  :  Bouchardat,  Compt. 
Rend.,  xxv.  274  ;  Dubrunfaut,  N.  Ann.  CTiim.  PTiys.,  xxi. 
169;  Compt.  Rend.,  xxix.  51,  ibid.,  xlii.  901,  803;  Lipp- 
man,  ScJieibler*  s  Neue  Zeit.,  iv.  304. 


*  Jodin,  Compt.  Rend.,  Iviii.  613. 


Compt.  Rend. ,  Ixxiv.  356. 


CHAPTER  IV. 

LACTOSE   OK  MILK-SUGAE  C12H22On. 

Lactin — Sucre  de  Lait,  FT. — Milchzucker,  Gr. 

LACTOSE,  an  isomer  of  cane-sugar,  is  found  in  the  milk 
of  the  mammalia.  The  only  instance  where  it  has  been 
met  with  in  a  plant  is  in  the  Achras  sapota,  which  fur- 
nishes lactose  and  another  fermentable  sugar  in  about 
equal  proportions  (Bouchardat,  fils  *). 

Milk-sugar  is  prepared  by  heating  milk  with  an  acid  or 
rennet,  separating  the  curd,  filtering  through  animal  char- 
coal, if  necessary,  and  evaporating  to  the  crystallizing- 
point.  It  occurs  in  commerce  generally  as  elongated,  crys- 
talline masses  containing  one  equivalent  of  water. 

The  Specific  Rotatory  Power  is  to  the  right,  and  va- 
ries much  with  the  concentration  of  the  solution.  It  has 
been  found  by  Hesse  f  to  be  for  a  solution  containing 

2  grm.  of  the  hydrate  to  100  c.c.  [a]  D  =  53.63°. 

3  "  "  "  =53.16°. 
5     "                         "                "  =52.90°. 

The  following  is  the  general  formula,  wherein  c  =  the  num- 
ber of  grammes  in  100  c.c.     c  =  2  to  12  ;  temp.  15°  C. 

[a]  D  =  54.54  -  .557c  +  .05475c2  -  .001774c3. 


Compt.  Rend.,  Aug.  14,  1871.          f  Ann.  Chem.  Pliarm.,  elxxvi.  100. 

91 


92  LACTOSE  OR  MILK-SUGAR. 

Schmoeger  *  gives  [a]  D  =  52.53°  for  a  36  per  cent,  solution 
at  20°  C. 

The  freshly -prepared  solution  shows  birotatiqn.  Alkalies 
alter  the  rotatory  power. 

Hydrated  Lactose  (crystallized  lactose).  C12H22On  ELO. 
— Crystallizes'  in  hard  white  or  transparent  four-sided 
hemihedral  prisms  belonging  to  the  right  prismatic  sys- 
tem. Loses  its  water  at  140°  to  145°.  Sp.  gr.,  1.543  at 
13.9°  C.  Permanent  in  the  air  up  to  100°. 

Composition. — 


Anhydrous. 

Hydrous. 

Carbon  

4.2  II 

4.0  oo 

Hydrogen  

6  4^ 

6.66 

51.46 

CQ.34 

100.00 

100.00 

Solubilities. — Milk-sugar  is  slightly  hygroscopic,  and 
soluble  in  five  or  six  parts  of  cold  and  2.5  parts  of  boiling 
water.  The  saturated  solution  produced  by  contact  with 
excess  of  the  sugar  has  a  density  of  1.055,  and  contains 
14.55  per  cent,  of  the  crystallized  substance.  This  solu- 
tion, when  left  to  evaporation,  deposits  crystals  as  soon  as 
the  density  reaches  1.063.  Lactose  dissolves  readily  in 
distilled  vinegar,  and  crystallizes  from  it  again  unaltered. 
It  is  insoluble  in  absolute  alcohol  and  ether  (Dubrunfaut  f). 

.  Action  of  Heat. — At  150°  C.  lactose  acquires  a  yellow 
color ;  at  160°  C.  gives  off  the  smell  of  caramel  and  loses 
slightly  in  weight ;  at  175°,  or  above,  it  is  partially  con- 
verted, with  loss  of  weight,  into  lacto-caramel  and  a  sub- 


*  Ber.  Chem.  Gesell,  xvi.  1922. 


f  Jahresber.  der  Chemie,  1856,  643. 


ACTION  OF  ACIDS.  93 

stance  insoluble  in  water  which  melts  at  203.5°  C.  (Lie- 
ben.*)  Crystallized  lactose,  when  carefully  heated,  gives 
off  12  per  cent,  of  water,  and  solidifies  on  cooling  to  a  crys- 
talline mass,  which  on  solution  regains  its  water  (Berze- 
lius). 

By  dry  distillation  lactose  yields  carbonic  acid,  combus- 
tible gases,  acetic  acid,  empyreumatic  oil,  and  charcoal. 
Heated  in  the  open  air  it  swells  up,  becomes  brown  and 
tenacious,  gives  off  the  odor  of  burnt  sugar,  and  leaves  a 
large  quantity  of  coal.  By  roasting,  gum  and  saccharic 
acid  are  produced.  In  aqueous  solution  the  sugar  is  de- 
composed when  heated  in  a  sealed  tube  to  100°-130°. 

Sulphuric  Aciil  (concentrated)  chars  lactose  at  100°. 
Heated  with  the  diluted  acid,  the  optical  rotatory  power  is 
increased  three- tenths,  gallactose  being  formed  (lactose  of 
Pasteur),  and  a  partially  dextro-rotatory,  non-fermentable 
substance  which  is  crystallizable  (Dubrunfaut).  Accord- 
ing to  Fudakowsky,f  two  sugars  are  produced  in  the  reac- 
tion, both  fermentable,  soluble  in  water,  dextro-gyrate, 
but  differing  by  their  solubility  in  alcohol.  The  sp.  rota- 
tory power,  after  warming  and  long  standing,  of  the  two 
are  respectively 

[a]  D  =  92.83°, 

[a]  D=  62.63°. 

((UNIVERSITY 
Both  are  birotatory.J  \5ji/FOR 

Nitric  Acid  diluted,  heated  with  milk-strga,Fr -gives 
mucic,  saccharic,  tartaric,  oxalic,  and  carbonic  acids.  The 
production  of  mucic  acid  in  this  way  is  particularly  cha- 
racteristic of  lactose.  Mtric  acid  may  act  on  lactose  in 

*  Jahresber.  der  Chemie,  1856,  643.  f  Zeits.  Anal.  Chem.,  [2]  iii.  32. 

\  See  also  Meissl,  Journ.  Pk.  Chem.,  xxii.  100. 


94  DEXTROSE,  LEVULOSE,  AND  INVERT-SUGAR. 

two  ways  :  1.  The  greater  part  of  the  sugar  may  be  con- 
verted into  mucic  acid,  which  then  undergoes  further  de- 
composition, yielding  tartaric  acid.  2.  A  small  portion  of 
the  sugar  is  changed,  as  in  the  case  with  sulphuric  acid, 
into  gallactose,  the  ultimate  product  of  the  reaction  being 
tartaric  acid.  Strong  nitric  acid  forms  an  explosive  nitro- 
substitution  compound. 

Concentrated  hydrochloric  acid  turns  lactose  brown, 
while  glacial  phosphoric  acid  forms  a  red  color,  but  does 
not  carbonize  it;  oxidized  by  potassium  chlorate  and 
iodic  acid.  Distilled  with  potassium  dichr  ornate  and  sul- 
phuric acid,  aldehyde  is  formed. 

Action  of  Alkalies.— Milk-sugar  absorbs  12,40  per 
cent,  of  ammonia  gas.  By  action  of  caustic  potash  a 
compound  is  obtained  from  which  acids  separate  the  lac- 
tose unaltered.  Triturated  with  potassium  hydrate  and 
water,  a  brown  liquid  containing  acetic  acid  is  obtained. 

A  solution  containing  three  molecules  of  free  alkali  to 
one  of  cupric  oxide,  with  tartaric  acid  or  an  alkaline  tar- 
trate,  yields,  when  heated  with  milk-sugar,  a  precipitate 
of  cuprous  oxide. 

Kitthausen*  has  obtained  from  milk,  by  the  action  of 
cupric  sulphate  and  potassium  hydrate,  a  carbohydrate 
which,  after  boiling  with  acids,  reduces  the  alkaline  solu- 
tion of  tartrate  of  copper.  A.  W.  Blyth  describes  two 
new  copper-reducing  bodies  from  milk  corresponding  to 
the  formulas  CH3O5  and  C3H3O4,  and  considers  them  to  be 
glucosides. 

Lactose  forms  more  or  less  well-defined  compounds  with 
potassium,  sodium,  calcium,  barium,  and  lead  oxides,  f 

*  Journ.  Prak.  Chemie,  neuefolge,  xv.  348. 

f  Honig  and  Rosenfeld,  Ber.  Chem.  OeselL,  xii.  47. 


FERMENTATION  OF  MILK-SUGAR.  95 

There  are  two  lime  compounds — one  soluble  and  contain- 
ing the  same  number  of  molecules  of  base  and  sugar,  and 
the  other  insoluble  and  basic.  Schutzenberger,*  by  action 
of  acetic  anhydride  on  milk-sugar,  obtained  octacetylated 
lactose 

CiaH14(C2HsO)8On  [«]j=31°, 

and  quadriacetylated  lactose 

C1,H1.(C,H.O)401,[X]j  =  60.r>. 

See  also  Herzfeld.f 

Lactose  does  not  unite  with  sodium  chloride  in  definite 
proportion. 

Fermentation.— Milk-sugar  ferments  at  30°  with  yeast, 
but  more  slowly  than  grape-sugar  or  dextrose,  yieldmg  al- 
cohol and  carbonic  acid.  Milk  ferments  also  spontaneous- 
ly without  the  addition  of  yeast,  producing  alcohol.  A 
solution  of  milk-sugar  in  contact  with  putrid  caseine  or 
gluten  gives  alcohol  and  lactic  acid,  the  milk-sugar  being 
not  previously  converted  into  gallactose.  Less  alcohol  is 
obtained  if  the  acid  is  neutralized  as  fast  as  formed. 

Erytlirozyme,  a  substance  obtained  from  madder,  causes 
milk-sugar  to  ferment,  giving  rise  to  carbonic,  formic, 
acetic,  and  succinic  acids,  hydrogen,  and  alcohol.J 

*  Ann.  Chem.  Pharm.,  clx.  91.  f  Scheibler's  Neue  Zeit.,  iii.  155. 

\  Schunck,  Journ.  Pk.  Chem.,  Ixiii.  23. 


CHAPTER  Y. 

DETERMINATION   OF   SPECIFIC   GRAVITY. 

THE  specific  gravity  or  density  of  solids  and  liquids  is  a 
ratio  expressing  their  weight  relative  to  an  equal  volume  of 
water  at  a  standard  temperature  ;  this  temperature  is  gen- 
erally that  of  water  at  its  greatest  density,  4°  C.,  though  15° 
C.  is  sometimes  adopted.  The  specific  gravity  of  water  is 
called  1,  and  that  of  all  other  solid  and  liquid  bodies  con- 
sists of  multiples  of  this,  whether  whole  numbers  or  frac- 
tions ;  thus,  the  specific  gravity  of  alcohol  is  .7938,  and 
that  of  gold  is  19.3— that  is,  a  volume  of  alcohol  or  gold, 
respectively,  weighs  .7938  and  19.3  times  as  mucli  as  an 
equal  bulk  of  water  at  4°  C. 

There  are  three  principal  methods  of  determining  the 
density  of  solids  and  liquids — viz.  :  1.  BY  THE  HYDROSTA- 

TIC  BALANCE  ;   2.  BY  THE  SPECIFIC-GRAVITY  FLASK  ;   and  3. 

BY  THE  AREOMETER.  All  of  these  are  the  same  in  principle, 
as  they  consist  in  ascertaining,  directly  or  indirectly,  the 
weight  of  a  body  in  air,  and  that  of  an  equal  bulk  of  water. 
The  Hydrostatic  Balance.— The  use  of  this  piece  of  ap- 
paratus depends  upon  the  following  physical  law,  first  enun- 
ciated by  Archimedes  :  A  solid  body  immersed  in  a  liquid 
loses  a  part  of  its  weight  equal  to  the  weight  of  the  dis- 
placed liquid.  Hence,  if  we  weigh  a  solid  on  an  ordinary 
balance,  first  in  air,  and  then  in  water  by  suspending  it  with 
a  fine  hair  or  silk  thread  from  the  scale-pan,  the  difference 
between  the  two  weighings  will  represent  the  weight  of  a 
volume  of  water  equal  to  that  of  the  solid ;  by  dividing  the 


HOUR'S  BALANCE. 


97 


weight  in  air  by  that  of  the  bulk  of  water  displaced,  the 
specific  gravity  is  obtained. 

Mohr  has  devised  a  form  of  the  hydrostatic  balance 
whereby  the  determination  of  the  density  of  liquids  may 
be  made  with  rapidity  and  accuracy  ;  the  principle  of  the 
apparatus  is  easily  derived  from  the  Archimedean  theorem  : 

Fig.  4. 


i;ooo 


It  is  evident  that  if  a  solid  is  weighed  while  suspended  in  a 
liquid,  that  the  decrease  in  weight  from  that  of  the  same 
body  in  air,  or  volume  displaced,  must  be  proportional  to 
the  density  of  the  liquid.  The  apparatus  (Fig.  4)  consists 


98  DETERMINATION  OF  SPECIFIC  GRAVITY. 

of  a  beam  which  is  in  equilibrium  in  air  when  the  sinker — 
a  glass  cylinder  enclosing  a  thermometer  and  hung  to  the 
extremity  of  the  arm  by  a  fine  platinum  wire — is  attached. 
It  is  necessary  to  have  the  balance  perfectly  horizontal,  and 
for  this  purpose  a  small  levelling-table  may  be  used  ;  there 
is  an  elevating-screw,  P,  by  which  the  beam  may  be  raised 
or  lowered  to  suit  the  requirements  of  the  operation.  The 
depth  to  which  the  sinker  should  descend  below  the  level 
of  the  liquid  under  examination  will  not  vary  much  from 
that  shown  in  the  figure.  The  weights  consist  of  a  series 
of  decimal  riders,  of  which  A  A,  (Fig.  4)  are  equal  to  each 
other,  and  likewise  equal  to  the  weight  of  the  volume  of 
distilled  water  displaced  by  the  sinker  at  15°  C.  ;  B  is  one- 
tenth  of  A,  and  C  is  one-hundredth.  A,  B,  and  C  are  hung 
on  the  graduated  beam.  When  the  sinker  is  immersed  in 
distilled  water  at  15°  C.,  and  the  rider  A,  is  on  the  end  of 
the  beam,  as  in  Fig.  4,  the  balance  is  in  equilibrium  and 
corresponds  to  the  density  of  1.000.  For  liquids  heavier 
than  water  the  other  riders  are  placed  on  the  beam,  Al  still 
hanging  on  its  extremity,  until  equilibrium  is  restored ; 
the  riders  when  thus  placed  have  following  values  : 

A,  =  1.000 

A  =    .100 

B   =    .010 

C   =    .001 

For  liquids  lighter  than  water  A,  is  taken  off  and  the 
balance  restored  with  the  other  riders.  Fig.  5  shows  ex- 
amples of  the  readings  with  different  densities.  The  sinker 
and  platinum  wire,  after  use,  should  be  cleaned  and  dried 
with  care. 

By  the  Specific-Gravity  Flask.— This  is  the  simplest 
and  at  the  same  time  one  of  the  most  accurate  methods  of 


THE  HYDROSTATIC  BALANCE. 


99 


taking  the  specific  gravity  of  solid  and  liquid  bodies.  The 
apparatus  is  a  tared  flask  holding  to  a  mark  on  the  neck 
a  determinate  weight  of  distilled  water  at  15°  C.  or  4°  C. 
The  liquid  to  be  examined  is  brought  to  the  required  tem- 
perature and  filled  into  the  flask  up  to  the  mark,  and  the 


0,147 


0,803 


0,910 


1,669 


1,846 


whole  weighed ;  the  last  weight,  after  subtracting  that  of 
the  flask,  is  that  of  a  bulk  of  the  liquid  equal  to  the  vol- 
ume of  water  whose  weight  is  known  ;  the  density  is  then 
obtained  on  dividing  the  former  by  the  latter. 
The  100  c.c.  flask  is  a  very  convenient  arrangement  for 


100  DETERMINATION  OF  SPECIFIC  GRAVITY. 

taking  specific  gravities,   the  weight  of  100  c.c.  of  any 
liquid,  divided  by  100,  being  its  specific  gravity. 

AREOMETKY. 

The  Areometer  (Ardometer,  Senkwage,  Gr. ;  Areo- 
metre,  Fr.) — The  areometer  consists  of  a  closed  tube  ex- 
panded below  into  a  bulb  the  lower  part  of  which  is  loaded 
to  maintain  the  instrument  in  an  upright  position  when 
floating. 

According  to  the  laws  of  hydrostatics,  a  body  immersed 
in  a  fluid  is  buoyed  up  with  a  force  exactly  equal  to  the 
weight  of  the  volume  displaced  ;  hence,  if  the  body  float, 
the  weight  of  the  bulk  displaced  is  equal  to  that  of  the 
floating  body  ;  the  weight  of  an  areometer  in  air  is,  there- 
fore, the  same  as  that  of  the  volume  of  liquid  displaced 
by  it  when  floating  freely. 

Areometers  may  be  divided  into  two  classes — viz.,  (1) 
those  Jiaving  constant  volume  and  variable  weight,  and 
(2)  tliose  of  variable  volume  and  constant  weight.  Hydro- 
meters of  the  first  class,  on  being  placed  in  the  liquid  to  be 
tested,  sink  to  a  fixed  mark  on  the  stem  by  means  of 
weights  added ;  from  these  weights  the  volume  displaced  is 
calculated.  Nicholson's  and  Fahrenheit's  hydrometers  are 
of  this  kind.  Those  of  the  second  class  are  provided  with  a 
scale  on  the  stem,  and  the  instruments,  when  used,  are 
allowed  to  sink  in  the  liquid  until  they  float  in  equilibrium, 
the  point  at  which  the  surface  of  the  liquid  cuts  the  scale 
indicating  either  directly  the  specific  gravity,  or,  in  the  case 
of  areometers  with  arbitrary  scale,  merely  a  degree  which 
does  not  show  directly  the  density.  In  regard  to  areome- 
ters with  variable  volume,  it  may  be  said  that  if  a  floating 
body  of  constant  weight  be  immersed  in  different  fluids, 


AREOMETRY.  101 

their  densities  will  be  in  inverse  ratio  to  the  volumes  dis- 
placed ;  the  less  dense  the  greater  the  displacement,  and 
vice  versa.  Suppose  we  float  a  hydrometer  weighing  50 
grammes ;  then  the  volume  of  liquid  displaced  by  it  will 
weigh  exactly  50  grammes.  ISTow,  with  fluids  of  various 
densities  the  50  grammes  will  correspond  to  volumes  in- 
versely as  the  density.  In  the  case  of  water  the  volume 
displaced  would  be  50  c.c.  =  50  grammes,  which,  divided 

by  the  weight  of  the  areometer,  gives  —  =  1.000    as    the 

oO 

specific   gravity ;   50   grammes   syrup  of  specific  gravity 

1.261  would  occupy  a  volume  of  39.6  c.c./-- 1-— ).     Accord- 

\l./&ol/ 

ingly,  the  division  of  the  scale  shown  by  areometers  corre- 
sponds to  volume  displaced,  and  either  shows  directly  the 
specific  gravity,  or  a  formula  may  be  obtained  by  which 
the  indications  of  the  arbitrary  scales  may  be  reduced  to 
specific  gravities. 

The  scales  of  areometers  of  variable  volume  are  even  or 
uneven— the  former  include  the  majority  of  hydrometers  in 
ordinary  use  ;  the  latter  are  those  in  which  the  graduations 
read  specific  gravities,  and  are  called  densimeters.  Even 
scale  hydrometers  for  use  in  the  arts,  and,  indeed,  for  sci- 
entific purposes,  have  some  advantages  over  those  reading 
specific  gravities.  The  scale  of  the  latter,  being  expressed 
in  decimal  fractions,  are  more  difficult  to  remember  and 
record  ;  for  example,  it  is  easier  to  remember  that  a  solu- 
tion is  25°  Baume  than  that  its  specific  gravity  is  1.2173. 
The  densimeter  is,  furthermore,  much  more  difficult  to  con- 
struct correctly,  and  consequently  more  costly.  The  scales 
of  all  areometers  should,  however,  be  based  on  fixed  and 
invariable  data,  so  that  the  specific  gravity  corresponding 


102  DETERMINATION  OF  SPECIFIC  GRAVITY. 

to  any  degree  may  be  calculated.  Such  data,  and  tables 
based  on  them,  are  given  in  another  part  of  this  work. 

As  areometers  are  used  for  two  diif erent  classes  of  liquids 
— those  denser  than  water,  which  increase  in  value  with 
the  density ;  and  those  less  dense,  which  contain  more  of 
the  valuable  constituent  the  lower  the  specific  gravity, 
water  at  a  standard  temperature  is  the  natural  zero-point 
for  hydrometer  scales ;  for  fluids  heavier  than  water  the 
degrees  will  read  downwards,  while  for  those  lighter  the 
readings  will  be  in  reverse  order  ;  in  either  case  the  num- 
ber of  divisions  of  the  scale  from  zero  will  increase  in  pro- 
portion to  the  amount  of  valuable  constituent  present  in 
the  solution  examined.  Hence  for  arbitrary  scales  the 
reading  is  natural,  easily  comprehended  and  remembered. 

The  form  of  the  part  of  the  hydrometer  below  the  sur- 
face of  the  liquid  may  vary,  but  it  should  be  symmetrical 
with  the  axis,  or  otherwise  the  instrument  would  not  float 
perfectly  upright,  but  would  lean  ;  the  lower  part  is  always 
more  or  less  expanded,  so  that  the  stem  may  not  be  of  inor- 
dinate length.  The  greater  the  volume  of  the  bulb  propor- 
tional to  that  of  the  stem,  the  greater  will  be  the  sensitive- 
ness of  the  instrument ;  that  is,  a  small  difference  in  den- 
sity or  displacement  will  correspond  to  a  large  space  on  the 
stem.  It  has  on  this  account  been  found  useful  to  graduate 
hydrometers  for  special  purposes  in  which  the  scale  ex- 
tends only  over  a  limited  field  of  density  ;  in  this  way  each 
degree  may  occupy  a  larger  space  and  may  be  divided  into 
fractions.  Examples  of  these  are  Baume's  hydrometers 
called  acidometers,  salinometers,  alcoholometers,  saccha- 
rometers,  etc.,  made  for  special  purposes  in  the  arts. 

Hydrometers  are  made  of  glass,  or  metal,  as  brass,  silver, 
or  G-erman  silver.  Glass  is  preferable  for  most  purposes 


VARIOUS  AREOMETERS.  103 

from  its  cheapness  and  the  ease  with  which  it  is  worked ; 
besides  which  air  bubbles  adhere  less  to  glass  than  metallic 
surfaces,  thus  lessening  one  of  the  greatest  sources  of  error 
inherent  with  the  use  of  hydrometers,  especially  when  dense 
solutions  are  operated  upon.  '  Another  advantage  of  glass 
is  the  impossibility  of  indenting  the  surface,  which  is  a 
source  of  error  to  which  metallic  areometers  are  peculiarly 
liable.  Glass  is  not,  however,  suitable  as  a  material  for 
very  sensitive  areometers,  because  the  extreme  smallness 
of  bore  it  is  necessary  to  give  the  stem  would  make  it  too 
fragile. 

The  areometers  of  variable  volume  in  common  use  essen- 
tially differ  in  the  manner  in  which  the  scale  is  divided. 
The  following  are  those  which  will  be  described  in  this 
work : 

I.  When  the    scale    indicates  volumes    displaced — Gay 

Lussac }s  volumeter  (even  scale). 
II.  When  the  scales  indicate  directly  specific  gravities — 

the  densimeter  (uneven  scale). 

III.  When  the  indications  of  the  scale    are    arbitrary — 

Baume1  s  hydrometer  (even  scale). 

IV.  When  the  scale  indicates  percentages  of  substance  in 

solution — Balling' s  saccJiarometer  (even  scale). 

GAY   LUSSAC'S   VOLUMETER. 

This  areometer  is  of  the  ordinary  form,  and  the  scale 
shows  directly  the  volume  displaced  of  the  liquid  tested 
with  it,  in  comparison  with  that  of  water  with  the  same  in- 
strument. Thus,  if  it  is  floated  in  a  solution  and  stands 
at  40°  on  the  scale,  this  indicates  for  the  same  weight, 
the  volume  of  water  being  100,  that  of  the  solution  would 
be  40  ;  whence  the  density  may  be  readily  calculated.  The 


104 


DETERMINATION  OF  SPECIFIC  GRAVITY. 


Fig 


100 


90 


70 


1,0 


1,1 


1,2 


1,3 


1,5 


6. 


H 


110 


100 


0,7 


0,8 


0,9 


point  to  which  the  instrument  sinks 
in  water  is  marked  100  on  the  scale. 
Above  and  below  this,  divisions  are 
made  of  such  a  kind  that  the  vol- 
ume of  the  stem  comprised  between 
two  successive  degrees  is  T-Jo  of  the 
total  volume  below  the  100°  mark. 
As  the  volumeter  is  more  exact  the 
larger  the  divisions  of  the  scale,  it  is 
advisable  to  have  it  made  in  two 
spindles,  one  for  liquids  heavier  than 
water,  with  the  100°  point  at  the  up- 
per part  of  the  scale,  Fig.  6,  A  ;  and 
another  for  liquids  lighter  than  wa- 
ter, with  the  100°  point  near  the  bot- 
tom, Fig.  6,  B. 

In  order  to  obtain  the  specific  gra- 
vity of  a  liquid  it  is  simply  necessary 
to  divide  the  volume  displaced  in  wa- 
ter 100,  by  the  number  on  the  scale 
to  which  the  apparatus  sinks.  The 
same  rule  applies  for  liquids  lighter 
than,  water.  Thus,  if  the  volumeter 
marks  120,  we  have  |$#,  or  -833.  In 
the  figure  the  scales  to  the  right 
and  left  are  those  of  the  volumeter 
with  the  corresponding  specific  gra- 
vities opposite.  It  is  seen  that  equal 
differences  in  volume  correspond  to 
unequal  differences  in  density. 

The  volumeter  has  a  great  ad- 
vantage over  the  densimeter  in  that 


DENSIMETER. 


105 


its  scale  is  even.  It  has  all  the  advantage  of  an  areo- 
meter with  arbitrary  scale,  its  degrees  being  whole  num- 
bers (though  reading  inversely  for  liquids  heavier  than 
water),  and  yet,  by  a  very  simple  calculation,  the  indica- 
tions may  be  converted  into  specific  gravities. 

The  table  below  gives  the  correspondence  of  the  volu- 
meter and  specific  gravities : 


Degree  of 
volumeter. 

Density. 

Degree   of 
volumeter. 

Density. 

50. 

2.OOO 

90.90 

I.  TOGO 

52.63 

.900 

100.00 

1.  0000 

55-55 

.800 

105.26 

.9500 

58.82 

.700 

III.  II 

.gOOO 

62.50 

.600 

117.64 

.8500 

66.66 

.560 

125  oo 

.8000 

71-43 

.400 

133-33 

.7500 

76.92 

.300 

142.85 

.7OOO 

83.33 

I.2OO 

THE  DENSIMETER. 

This  instrument  reads  directly,  without  calculation,  the 
specific  gravity  of  the  liquid  in  which  it  floats.  The  scale 
is  so  made  that  the  point  to  which  the  hydrometer  sinks  in 
distilled  water  at  standard  temperature  is  marked  1.000, 
and  the  graduation  for  liquids  lighter  than  water  is  carried 
above  this  point,  and  for  liquids  heavier  than  water  in  the 
reverse  direction.  The  finer  hydrometers  of  this  kind 
have  the  scale  divided  between  two  or  more  spindles,  so 
that  the  increased  length  of  stem  gives  room  for  a  more 
accurately-divided  scale.  When  the  densimeter  consists 
only  of  the  hydrominor  and  hydromajor  spindles,  the  1.000 
point  is  placed  with  the  first  at  the  bottom  of  the  areo- 
meter, and  at  the  top  with  the  second. 

Ventzke's  Areometer  is  a  densimeter  with  a  bulb  enor- 


106  DETERMINATION  OF  SPECIFIC  GRAVITY. 

mously  enlarged  compared  with  the  stem,  which  is  very 
short  and  thin,  in  order  that  the  instrument  may  have 
great  sensitiveness.  The  middle  of  the  stem,  is  marked 
with  density  of  1.100,  and  divisions  showing  small  differ- 
ences in  density  are  carried  above  and  below  this  point. 
The  areometer  is  used  in  Ventzke's  process  for  determin- 
ing sugar  by  the  optical  saccharimeter,  and  also  for  esti- 
mating the  water  in  sugars  and  syrups  from  their  density 
when  in  solution  (see  page  147). 

BAUME'  s  HYDEOMETEE. 

Baume' s  hydrometer  is  generally  made  of  glass,  of  the 
ordinary  form,  and  loaded  with  shot  or  mercury.  The 
scale  may  be  either  engraved  on  the  stem,  or  of  paper  en- 
closed within  it,  as  is  the  form  of  the  cheaper  kinds. 
There  are  two  entirely  distinct  Baume  hydrometers,  gradu- 
ated on  different  principles,  the  divisions  of  their  scales 
not  being  directly  convertible  into  each  other.  They  are 
the  liydromajor  and  the  liydrominor  spindles.  For  the 
hydromajor  instrument  (pese  sel,  pese  acide)  the  point 
marked  15°  on  the  scale  was  fixed  by  Baume  at  the  place 
on  the  scale  where  it  sinks  in  a  solution  of  common  salt 
made  by  dissolving  fifteen  parts  by  weight  in  eighty-five 
parts  of  water.  The  space  between  this  and  zero  was 
divided  into  fifteen  equal  parts,  and  divisions  of  the  same 
size  were  continued  below  15°  to  the  bulb. 

In  the  hydrominor  spindle  (pese  spirit)  the  point  on 
the  stem  to  which  it  sinks  in  water  is  marked  10,  while  the 
zero  is  where  it  stands  in  a  solution  of  ten  parts  common 
salt  in  ninety  parts  of  water.  The  density  of  this  solution 
is  1.0847.  The  distance  between  0°  and  10°  is  divided  into 


BAUME'S  AREOMETER.  107 

10  equal  parts,  and  this  division  is  extended  to  the  rest  of 
the  scale. 

Standard  of  Graduation. — There  has  always  been 
some  uncertainty  about  the  standard  proposed  by  Baume 
for  fixing  the  points  for  the  graduation  of  his  areometers. 
He  himself  prescribes  the  use  of  pure  and  dry  salt,  which 
would  yield  a  solution  of  sp.  gr.  1.109  for  the  hydromajor 
spindle.  Other  authorities  direct  the  use  of  common 
salt  which  contains  varying  quantities  of  moisture  and 
from  two  to  eight  per  cent,  of  other  impurities,  varying 
with  the  quality.  Hence  it  is  very  evident  that  hydro- 
meters graduated  by  the  two  methods  will  have  scales  not 
comparable.  If,  however,  the  directions  of  Baume  are 
rigidly  adhered  to,  and  a  solution  of  chemically-pure  salt, 
of  sp.  gr.  1.109  at  15°,  is  used,  there  could  be  no  better  or 
more  unvarying  standard.  A  new  method  for  graduat- 
ing these  hydrometers  was  introduced  by  Gay  Lussac,  by 
which  the  zero-point  corresponds  to  distilled  water  at  4° 
C.,  and  the  degree  at  which  they  stand  in  pure  mono- 
hydrated  sulphuric  acid  is  made  66°  at  15°  C.,  the  inter- 
mediate part  of  the  scale  between  these  two  points  being 
divided  in  66  equal  parts.  At  present  all  Baume' s  hydro- 
meters are  graduated  on  Gay  Lussac' s  plan,  except  that 
both  of  the  fixed  points  are  generally  taken  at  the  tempe- 
rature of  15°  C. ;  the  difference  between  this  way  of  gradu- 
ating and  the  unmodified  one  of  Gay  Lussac  is  too  small 
to  be  taken  into  consideration,  unless  in  very  exceptional 
circumstances.  The  chief  practical  objection  to  this 
method  is  that  the  oil  of  vitriol  of  commerce  used  by 
makers  of  these  instruments  varies  in  density  considera- 
bly, as  coming  from  different  sources  ;  also,  the  densities  of 
the  pure  acid,  as  given  by  various  authorities,  differ  suffi- 


108  DETERMINATION  OF  SPECIFIC  GRAVITY. 

ciently  to  cause  a  serious  error  in  the  graduation  based  on 
these  data.  These  differences  are  probably  owing  for  the 
most  part  to  the  varying  temperature  at  which  the  speci- 
fic gravity  was  taken.  That  given  by  Gay  Lussac  is 
1.8427  at  15°  C.,  and  is  entirely  reliable.  It  will  be  seen 
that  the  areometers  graduated  with  oil  of  vitriol,  with- 
out regard  to  temperature,  or  a  strict  determination  of 
the  density  of  the  graduating  liquid  so  that  it  may  be  the 
same  as  the  figure  given  above,  will  show  a  notable  error  ; 
but  if  regard  is  paid  to  the  necessary  conditions  of  the 
operation,  and  these  conditions  are  the  same  in  all  cases, 
the  hydrometers  agree  very  closely  with  each  other,  and 
their  readings  can  always  be  converted  into  specific  gravi- 
ties by  appropriate  formulas. 

A  good  hydrometer  has  a  stem  of  the  same  calibre 
throughout,  and  the  scale  equally  divided.  The  accuracy 
in  these  respects  may  be  readily  determined  with  a  pair  of 
calipers  and  compasses. 

Reduction  of  Scale  to  Specific  Gravity.-  Though 
the  scale  of  the  Baume  instrument  is  arbitrary,  yet  the 
specific  gravity  corresponding  to  any  degree  may  be  cal- 
culated. Tables  of  these  equivalents,  in  the  case  of  hydro- 
meters for  liquids  heavier  than  water,  met  with  in  the 
books,  show  great  discrepancies,  for  the  reason  that  some 
are  calculated  by  the  following  formula  given  by  Francceur  : 


152  -d 

in  which  P  =  the  density;  d  =  the  degree  Baume. 
This  is  the  correct  formula  when  the  graduation  is  effected 
by  the  original  method  of  Baume  with  a  solution  of  salt. 
When  Gay  Lussac'  s  method  is  used  with  sulphuric  acid  of 
sp.  gr.  1.8427  at  15°  C.,  the  'formula  becomes 


CORRECTION  FOR  TEMPERATURE. 


109 


144.3 


144.3  -  d 

Tables  calculated  after  (2)  are  the  only  ones  practically  use- 
ful, as  the  instruments  are  no  longer  graduated  with  salt 
solution. 
The  formula  for  the  hydrominor  hydrometer  is 


(3) 


-p i^u 

"  136~+d 


The  following  table  given  by  Bourgougnon  *  shows  the 
specific  gravities  corresponding  to  degrees  Baume  for 
liquids  heavier  than  water,  at  15°  C.,  calculated  according 
to  formula  (2)  : 


Deg.  B. 

Sp.  Gr. 

Deg.  B. 

Sp.  Gr. 

Deg.  B. 

Sp.  Gr. 

Deg.  B. 

Sp.  Gr. 

O 

1.  0000 

19 

.1516 

38 

•  3574 

57 

1.6527 

I 

1.0069 

20 

.1608 

39 

.3703 

58 

1.6719 

2 

1.0140 

21 

.1702 

40 

•3834 

59 

1.6915 

3 

1.  0212 

22 

.1798 

41 

.3968 

60 

I.7"5 

4 

1.0285 

23 

.1895 

42 

.4104 

61 

I.732I 

5 

1.0358 

24 

.1994 

43 

.4244 

62 

I.753I 

6 

1.0433 

25 

.2095 

44 

.4386 

63 

1.7748 

7 

1.0509 

26 

.2197 

45 

•4530 

64 

1.7968 

8 

1.0586 

27 

.2301 

46 

.4678 

65 

1.8194 

9 

1.0665 

28 

.2407 

47 

.4829 

66 

1.8427 

10 

1.0744 

29 

.2514 

48 

•4983 

67 

1.8665 

ii 

1.0825 

30 

.2624 

49 

.5140 

68 

1.8909 

12 

1.0906 

31 

•2735 

50 

•  5301 

69 

1.9161 

13 

1.0989 

32 

2849 

51 

.5465 

70 

1.9418 

14 

I.I074 

33 

.2964 

52 

.5632 

7i 

1.9683 

15 

I.II59 

34 

•  3081 

53 

.5802 

72 

1-9955 

16 

1.1246 

35 

•  3201 

54 

.5978 

73 

2.0235 

17 

I-I335 

36 

.3323 

55 

•  6157 

74 

2.0523 

18 

I.I424 

37 

•3447 

56 

.6340 

75 

2.0819 

*  Proc.  Am.  Chem.  Soc.,  vol.  i.,  No.  5,  p.  55 


110 


DETERMINATION  OF  SPECIFIC  GRAVITY 


The  table  for  liquids  lighter  than  water  is  calculated  by 
formula  (3) : 


Deg.  B. 

Sp.  Gr. 

Deg.  B. 

Sp.  Gr. 

Deg.  B. 

Sp.  Gr. 

i  Deg.  B. 

Sp.  Or. 

IO 

I.OOO 

23 

.918 

36 

.849 

!  49 

.789 

II 

•993 

24 

.913 

37 

.844 

50 

.785 

12 

.986 

25 

.907 

38 

.839 

5i 

.781 

13 

.980 

20 

.901 

39 

.834 

52 

•777 

14 

•973 

27 

.896 

40 

.830 

53 

•  773 

15 

.967 

28 

.890 

41 

.825 

54  i   -768 

16 

.960 

2Q 

.885 

42 

.820 

55 

.764 

17 

•954 

30 

.880 

43 

.816 

56 

.760 

18 

.948 

31 

.874 

44 

.811 

57 

•  757 

IQ 

•  942 

32 

.869 

45 

.807 

58 

•753 

20 

•  936 

•  33 

.864 

46 

.802 

59 

•  749 

21 

•930 

34 

.859 

47 

.798 

60 

•  745 

22 

.924 

35 

.854 

48 

•794 

Correction  for  Temperature. — As  the  areometer,  es- 
pecially in  the  sugar  industry,  is  often  used  at  tempera- 
tures above  the  ordinary,  it  is  desirable  to  obtain  a  correc- 
tion that  will  serve  to  reduce  the  readings  to  the  degree  of 
heat  at  which  the  instruments  are  graduated.  A  correction 
amply  accurate  enough  for  ordinary  purposes,  or,  indeed, 
to  any  purpose  to  which  this  hydrometer  is  itself  suited^ 
may  be  deduced  from  the  results  of  the  following  experi- 
ments given  in  foot-note.* 

When  the  temperature  is  above  15°  C.  or  62°  F.,  the  pro- 
duct of  the  number  of  degrees  in  excess,  multiplied  by 
.0471  or  .0265,  is  added  to  the  hydrometer  reading;  when 
it  is  below  the  standard  temperature,  it  is  subtracted  ;  or 
the  correction  of  TV  degree  Baume  for  each  difference  of 
two  degrees  Centigrade  may  be  used. 

BALLING'S  AREOMETEE. 
The  readings  of  this  areometer,  sometimes  called  Bal- 


*  Molasses  of  two  densities  and  a  strong  syrup  of  cane-sugar  were  heated 


BALLING'S  SACCHAEOMETER.  HI 

ling's  saccTiarometer,  indicate  directly  the  percentage  of 
pure  sugar  or  solid  matter  dissolved.  Thus,  if  it  is  floated 
in  a  solution  of  pure  cane-sugar  and  sinks  to  30°,  the  liquid 
contains  thirty  parts  of  sugar  and  seventy  parts  of  water. 
If  the  solution  contains  other  matters  besides  pure  sugar, 
the  readings  show  percentages  of  dissolved  matter  or  im- 
pure sugar.  The  form  is  that  of  a.  bulb  loaded  with  mer- 
cury, carrying  a  long  stem  on  which  is  the  scale.  For 
accurate  instruments  the  whole  scale  is  not  on  one  spindle, 
but  there  are  three,  one  embracing  the  scale  from  zero  to 
30°,  the  second  from  25°  to  60°,  and  the  third  from  55°  to 
90°.  The  degrees  are  divided  into  halves  or  fifths  to  allow 
of  more  exact  results. 

Balling,  an  Austrian  chemist,  originated  this  hydro- 
meter, and  made  careful  determinations  of  the  specific  gra- 
vities of  sugar  solutions  corresponding  to  various  percent- 
ages of  sugar  dissolved,  as  did  also  Meman  and  Geiiach. 

successively  to  different  temperatures,  and  the  readings  of  the  hydrometer  care- 
fully taken  and  averaged. 

1.  Molasses  stood  : 

At  11°  C.  —  34.3°  B.   1 

4(T  T        *2  Q°  B  Average  for 

^U        \J.    -    O^.U        JJ.  I     -I  O    /I  T£C  £ 

56°  a-  32.a°  B.  r1  c-=^;!eienoeof 

79°  0.-  31.2°  B.    j  -°456  B' 

2.  Molasses  : 

At  13°  C.-  15.6"  B. 


-047m 

3.  A  symp  of  cane-sugar  stood  : 

At  12°  C.  —  33.25°  B.  ]  Average 

48°  C.  —  31.20°  B.  U°  C.  =  a  difference  of 
77°  C.  —  30.10°  B.  J  .0484°  B. 

Average  of  the  three  estimations  : 

1°  C.  =  .0471°  B. 
1°  F.  =  .0265°  B. 


112 


DETERMINATION  OF  SPECIFIC  GRAVITY. 


Later,  Brix  has  recalculated  Balling's  table,  making  some 
corrections,  and  now  the  instrument  is  made  according  to 
the  results  of  Brix,  and  is  generally  known  as  the  Brix 
saccharometer.  The  terms  Britf 's  or  Balling*  s  areometer 
or  saccharometer  will  'be  used  indifferently  in  this  work. 

Error  due  to  Impurities. — It  is  evident  that  when 
Balling's  saccharometer  is  used  on  impure  sugar  solutions, 
the  indications  will  be  incorrect  in  proportion  as  the 
specific  gravity  of  the  impurities  differs  from  that  of  cane- 
sugar,  and  that  the  error  will  also  be  proportionally  greater 
as  the  impurities  exist  in  larger  quantity  in  comparison 
with  the  cane-sugar.  The  following  table  shows  the  den- 
sity of  some  of  the  leading  impurities  contained  in  cane 
or  beet  juice : 


20  per  cent, 
solution. 

25  per  cent. 

solution. 

I  0833 

IO6O7 

I  0831 

.IO2IO 

Calcium  acetate  

I  08  7J. 

I  I^O 

1.1736 

222O 

Sodium  sulphate  

I  0807 

IOI7 

1.1418 

l8l2 

Potassium  nitrate                            

I   I^^Q 

Another  table,  given  by  Frese,*  shows  the  same  class  of 
facts.  The  solutions  each  contain  one  per  cent,  of  sub- 
stance : 


1  Frese,  Beitrage  der  Zuckerfabrikation. 


SOURCE  OF  ERROR. 


113 


Sp.  Gr. 

Per  cent.  Balling. 

1.0086 

2.15 

'           hydrate     .        .  .             

1.0088 

2.  2O 

'                "      neut   with  PO4H3     . 

1.0156 

•3    QO 

'           nitrate             .  .             

1.0062 

I    55 

'          hydrate  neut.  with  citric  acid  .  . 
Sodium  carbonate                       .        .        . 

I.  OIIO 
I  0084 

2-75 
2  IO 

i  .  oo-j  j 

I.IO 

1.0070 

1.75 

phosphate   .  .  .      ... 

1.0040 

I.OO 

1.0036 

.QO 

1.0036 

.90 

With  grape-sugar  the  density  for  strong  solutions  is  suffi- 
cient to  make  a  difference  of  about  one  per  cent.,  while  for, 
some  of  the  salts  the  error  is  enormously  greater. 

This  source  of  inaccuracy  will  always  prevent  Balling's 
saccharometer  from  giving  perfectly  reliable  results  in  solu- 
tions containing  much  impurity,  though  there  can  be  no 
doubt  of  its  great  value  for  ordinary  technical  work,  even 
on  the  lower  products  of  the  fabricant  and  refiner. 

Correction  for  Temperature. — This  correction  is 
given  in  the  following  table,  arranged  from  that  of  Stam- 
mer.* It  is  to  be  observed  that  when  the  temperature  of 
the  solution  operated  upon  is  lower  than  17£°  C.  (63|°  F.), 
the  correction  is  to  be  subtracted  from  the  reading  of  the 
areometer;  when  above  17J°  it  is  to  be  added.  If  the 
saccharometer  is  graduated  at  15°  C.  instead  of  17J°,  the 
difference  made  by  using  the  table  given  below  is  too  small 
to  be  considered  in  ordinary  work  : 


Lehrbucfy  der  Zuckerfabrikation  ;  Erganzungband,  page  60, 


114 


DETERMINATION  OF  SPECIFIC  GRAVITY. 


CORRECTION  FOR. THE  READINGS  OF  BALLING'S  SACCHAROMETER,  ox 
ACCOUNT  OF  TEMPERATURE. 


Temp. 

Per  cent,  of  sugar  in  solution. 

c. 

F. 

0 

5 

10 

15 

20 

25, 

30 

35 

40 

50     60 

70 

75 

To  be  subtracted  from  the  degree  read. 

o° 

32° 

•  17 

.30 

.41 

•52 

.62 

.72 

.82 

.92 

.98 

i.  ii 

1.22 

1.25 

1.29 

5 

4i 

.23 

•30 

•  37 

.44 

•52 

•59 

.65 

.72 

•  75 

.80 

.88 

.91 

•94 

10 

5i 

.20 

.26 

.29 

.33 

.36 

•39 

.42 

•45 

.48 

•  50 

•  54 

•  58 

,6ij 

ii 

52 

.18 

•23 

.26 

.28 

.31 

•34 

.36 

•39 

•41 

•  43 

•47 

•  50 

•  53 

12 

53-6 

.16 

.20 

.22 

•24 

.26 

•29 

oi 

•  33 

.34 

.36 

.40 

.42 

.46 

J3 

55-4 

.14 

.18 

.19 

.21 

.22 

.24 

.26 

.27 

.28 

.29 

•33 

•  35 

•39 

14 

57-0 

.12 

•15 

.16 

•17 

.18 

.19 

.21 

.22 

.22 

.23 

.26 

.28 

•32 

15 

59-° 

.09 

.11 

.12 

.14 

.14 

•15 

.16 

•17 

.16 

•  17 

.19 

.21 

•25 

16 

61.0 

.06 

.07 

.08 

.09 

.10 

.10 

.11 

.12 

.12 

.12 

.14 

.16 

.18 

17 

62.5 

.02 

.02 

.03 

•03 

•03 

.04 

.04 

.04 

.04 

.04 

.05 

•05 

.06 

To  be  added  to  the  degree  read. 

18 

64.4 

.02 

•03 

•03 

•03 

•03 

•03 

•03 

•03 

•03 

•03 

•03 

.03 

.02 

J9 

66.2 

.06 

.08 

.08 

.09 

.09 

.10 

.IO 

.10 

.IO 

.10 

.10 

.08 

.06 

20 

68.0 

.11 

.14 

•15 

•17 

•17 

.18 

.18' 

.18 

.19 

.19 

.18 

•J5 

.11 

21 

70.0 

.16 

.20 

.22 

.24 

.24 

.25 

•25 

•25 

.26 

.26 

.25 

.22 

.18 

22 

71-6 

.21 

.26 

.29 

•31 

'.31 

.32 

•32 

•32 

•33 

•34 

•32 

.29 

.25 

23 

73-4 

•27 

•32 

•  35 

•37 

.38 

•39 

•39 

•39 

.40 

.42 

•39 

.36 

•33 

24 

75-o 

•32 

.33 

.41 

•43 

.44 

.46 

.46 

•47 

.47 

•50 

.46 

•43 

40 

25 

77.0 

•  37 

.44 

•47 

•49 

.51 

•  53 

•54 

.55 

•  55 

.58 

•54 

•51 

.48 

26 

79.0 

•43 

•50 

•  54 

•56 

.58 

.60 

.61 

.62 

.62 

.66 

.62 

•58 

•55 

27 

80.6 

.49 

•  57 

.61 

.63 

.65 

.68 

.68 

.69 

•  70 

•74 

.70 

.65 

.62 

28 

82.4 

•  56 

.64 

.68 

.70 

•  72 

.76 

.76 

.78 

.78 

.82 

•78 

.72 

.70 

29 

84.0 

.63 

•  71 

•  75 

•  78 

•79 

.84 

.84 

.86 

.86 

.90 

.86 

.80 

.78 

30 

86.0 

.70 

•  78 

.82 

.87 

.87 

•92 

.92 

•94 

•94 

.98 

.94 

.88 

.86 

35 

95-0 

1.  10 

1.17 

1.22 

1.24 

1.30 

1.32 

1-33 

1-35 

1.36 

1-39 

1-34 

1.27 

1.25 

40 

104.0 

1.50 

1.61 

1.67 

1.71 

1-73 

1.79 

1.79 

1.80 

1.82 

1.83 

1.78 

1.69 

1.65 

50 

122 

2.65 

2.71 

2.74 

3.78 

2.80 

2.80 

2.80 

2.80 

2.79 

2.70 

2.56 

2.51 

60 

140 

.... 

3.87 

3-88 

3.88 

3-88 

3.88 

3-88 

3-88 

3-9° 

3-82 

3-70 

3-43 

3-4i 

7O 

158 

5.18 

5.20 

5.14 

5.13 

5.10 

5.08 

5.06 

4.QO 

4.72 

4-47 

4-35 

/  w 

80 

J.  3\J 

I76 

6.62 

6.59 

6.54 

6.46 

6.38 

6.30 

6.26 

T"  V 

6.06 

5-82 

550 

5-33 

According  to  observations  of  Gerlach,  the  correction  for 
temperature  varies  with,  the  concentration  of  the  solution 
and  the  range  of  temperature  as  shown  in  the  table. 


VIVIEN'S  SACCHAROMETER.  115 

A  very  convenient  form  of  the  Balling  saccharometer  is 
to  have  the  thermometer  forming  part  of  the  areometer, 
with  its  stem  enclosed  within  that- of  the  latter.  The  ther- 
mometer is  graduated  into  degrees  Centigrade  on  one  side 
of  the  stem,  and  into  the  corresponding  corrections  for 
some  of  the  more  common  temperatures  on  the  other ;  so 
that  not  only  is  the  taking  of  the  temperature  as  a  separate 
operation  dispensed  with,  but  also  the  trouble  of  consult- 
ing the  table.  In  this  way  the  corrected  degree  Balling 
may  be  obtained  by  two  readings  and  a  simple  mental  ope- 
ration. 

Vivien's  Saccharometer. — This  areometer  has  two 
scales,  one  showing  the  number  of  kilos,  of  sugar  in  the 
hectolitre  of  sugar  solution,  and  the  other  the  correspond- 
ing specific  gravities.  It  consists  of  three  separate  spin- 
dles, the  first  having  a  range  from  1  to  1.025  sp.  gr.,  the 
second  from  1.025  to  1.05,  and  the  third  from  1.05  to  1.075. 
The  instrument  is  intended  especially  for  beet-juice  or 
other  thin  saccharine  liquids. 

The  following  table  gives  the  percentages  of  sugar,  or 
degree  Balling,  of  sugar  solutions,  with  the  correspond- 
ing densities  and  degrees  Baume.  It  was  calculated  by 
Mategczek,  Scheibler,  and  Stammer.* 

*  ZeitscTirift  fur  Zuckerindustrie  des  Deutschen  Reiches,  xv.  583,  xx.  269  ; 
Stammer,  Zuckerfabrikation,  28  et  seq. 


116 


DETERMINATION  OF  SPECIFIC  GRAVITY. 


TABLE  SHOWING  THE  RELATION  OF  PERCENTAGES,  SPECIFIC  GRAVITIES,  AND 
DEGREES  BAUME  IN  CANE-SUGAR  SOLUTIONS. 


Per  cent,  of 
Sugar. 

tC.y" 

II 

Per  cent,  of 

Su^ar. 

|J 

11 

Ow 

0 

I5 

I 

1J 

£ 

tc  ^ 

1 

Degree 

Laume. 

o.o 

i.oooo 

o.o 

7-3 

1.0290 

4.1 

14.6 

1.0596 

8.1 

[21-9 

1.0918 

12.  1 

.1 

i.  0003 

0.06 

•4 

.   1.0294 

•7 

1.0600 

8.15 

2_>.0 

1.0923 

12.2 

.2 

i  .0007 

O.II 

'  -5 

1.0298 

4-2 

.8 

1.0604 

8.2 

.1 

1.0927 

12.2 

•3 

•4 

I  .  OOI  I 

1.0015 

0.17 

0.22. 

.6 
•7 

i  .  0302 
i  .  0306 

4.2 

4-3 

•9 
15.0 

1.0609 
1.0613 

8-3 

8-3 

.2 

•3 

1.0033 
.0036 

12.3 
12.3 

.5 

1.0019 

0.28 

.8 

1.0310 

4-3 

.  i 

1.0617 

8.4 

•4 

.0941 

12.4 

.6 

1.0023 

0-33 

•9 

1.0314 

4-4 

.2 

1.0621 

8.4 

.0945 

12.4 

•  7 

1.0027 

0-39 

8.0 

1.0318 

4-4 

•  3 

i  .  0626 

8-5 

.5 

.09^0 

12.5 

.8 
•9 

1.0031 

1.0034 

0.44 

0-5 

.2 

1.0322 
1.0327 

4-5 

1 

i  .  0630 

8-5 
8.6 

i 

.0954 
.0959 

llf 

I.O 

1.0038 

0.55 

•3 

1-0331 

4.6 

.6 

i  .  0639 

8.65 

.-9 

.0961 

12.7 

,  i 

1.0042 

0.6 

•4 

1-0335 

4-7 

•  7 

3  .0643 

8-7 

23-0 

.0968 

12.7 

.2 

I  .0046 

0.7 

•5 

1.0339 

4-7 

.8 

I.0647 

8.8 

•i 

•0973 

I2.t5 

.3 

I  .0050 

0-7 

.6 

1-0343 

4.8 

•9 

1.0652 

8.3 

.2 

.0077 

12.8 

•4 

I  .oo=<4 

0.8 

.7 

1-0317 

4-8 

j  16.0 

I.c6s6 

8-9 

•  3 

12.9 

•  5 

I  .  0058 

0.8 

.8 

1.0351 

4-9 

i.c6Co 

8-9 

•4 

.'0^86 

12.9 

.6 
.7 

i  .  0062 
i.co65 

o-9 
o-9 

,* 

1-0355 
I.  03  59 

4-9 
5-o 

.2 

•3 

1.0665 
1.0669 

9  o 
9.0 

.0991 

.0996 

13.0 
13.0 

.8 
•9 

i.  0070 
1.0074 

I.O 

1.05. 

.1 

.2 

1.0364 
1.0368 

5-05 

•4 

•-5 

I  Io678 

•i 

.  looo 
.1005 

13.1 
13-15 

2.Q 

1.0077 

i.i 

•3 

1.0372 

5^2 

.6 

i  .0682 

9.2 

•9 

13.2 

.1 

i.  0081 

1.2 

•4 

1.0376 

5-2 

•7 

1.0687 

9-25 

24.0 

.  1014 

13.3 

.2 

1.0085 

1.2 

.5 

i  .  0380 

5-3 

.8 

1.0691 

9-3 

.1 

.1019 

13.3 

•  3 

1.0089 

i  -3 

.6 

1.0384 

5-3 

•9 

1.0695 

9-4 

.2 

.1023 

13-4 

•4 

1.0093 

i-3 

•  7 

1.0388 

5-4 

;  17-0 

1.0700 

9-4 

•  3 

.1028 

13-4 

•  5 

1.0097 

.8 

1-0393 

5-4 

i      •  i 

1.0704 

9  5 

•4 

.1032 

.6 

I.OIOI 

I  -4 

•9 

1.0397 

5-5 

.2 

1.0709 

9-5 

•5 

.1037 

13-5 

.7 

.  I.OIC5 

I  .  ^ 

i  lo.o 

1.0401 

5-55 

•  3 

1-0713 

0.5 

.0 

.1042 

13.5 

.8 

I.OICQ 

i-  S5 

.1 

1.04  5 

5-6    , 

•4 

1.0717 

9-6 

•7 

.10.16 

13.6 

•9 

1.0113 

1.6 

.2 

1.0409 

5-7 

•5 

1.0722 

9-7 

•  1051 

13-7 

3.0 

i  .  01  1  7 

i  ,  7 

•3 

1.0413 

5-7 

.0 

1.0726 

9-75 

•9 

13-75 

.2 

I.OI2I 

I  .0125 

1:1 

.4 

1.0418 
1.0422 

5-8 
5-8    ' 

:l 

1.0730 
1-0735 

9.8 
9-9    ; 

25:? 

!iofo 

.1065 

13.8 

13.9 

.3 

1.0129 

1.8 

is" 

i  .0426 

5-9 

•9 

1-0739 

9-9 

1         .2 

.  1070 

13-9 

•  4 

1.0133 

1.9 

•7 

1.0430 

5  9 

I3.o 

1.0744 

lo.o 

•3 

.1074 

14.0 

•  S 

I.  0137 

1.9      1 

.8 

1-0434 

6.0 

.1 

1.0743 

10.0 

:       -4 

.1079 

14.0 

.6 

1.0141 

2.0 

•9 

1.0439 

6.05 

.2 

1-0753 

10.  I 

•5 

.1083 

14.1 

•  7 

I.  0145 

2.0 

II.  0 

1-0443 

6.1    i 

•3 

1.07-7 

10.  I'   ! 

.6 

.1088 

14.1 

.8 

1.0149 

2.1 

.1 

1.0447 

6.2      i 

•4 

1.0761 

10.2 

,7 

1093 

14.2 

•9 

1.0153 

2.2        j 

.2 

1.0451 

6.2    ! 

•5 

1.0766 

10.2 

.0 

1097 

14.2 

4.0 

1.0157 

2.2 

•  3 

1.0455 

C-3        ' 

.6 

1.0770 

10.3    ! 

•9 

1  102 

14-3 

.1 

I.  0161 

2-3 

•4 

I.04J9 

6.3 

•  7 

1.0775 

10.35 

26.0 

1107 

14-35 

.2 

I  .0165 

2-3 

•5 

1.0464 

6.4 

.8 

1.0779 

10.4 

.1 

IIII 

14.4 

•3 

1.0169 

2-4 

1.0463 

6.4    1 

•9 

1.0783 

10.5 

.2 

1116 

14.5 

•4 

1.0173 

2-4 

•7 

i  .  0472 

6.5 

19.0 

i  .0788 

10*5 

•  3 

1  121 

14-5 

.5 

1.0177 

2  -5 

•8 

1.0476 

6.  55  ' 

.1 

1.0792 

10.6 

•  4 

1125 

14.6 

.6 

1.0181 

2.6 

•9 

1.0481 

6.  6 

.2 

1.0797  • 

10.5 

•5 

1330 

14.6 

.7 

1.0185 

2.6 

12.0 

1.0^85 

6  7 

.3 

-  i.  0801 

10.7 

.SJ 

1135 

14.7 

.8 

1.0189 

2-7 

.1 

1.0489 

6.7  ; 

•4 

i.  0806 

10.7 

•7 

1140 

14-7 

•9 
5-o 
.1 

1.0193 
1.0197 

I.O2OI 

a 

2.8 

.2 

•3 

•4 

i  0493 
1.0497 
1.0502 

6.8    ' 
6.8 
6-9 

1 

•7 

1.0810 
1.0815 
i.oSig 

10.8 

10.85 
10.9 

.8 
*    -9 
27.0 

"44 

1.1149 
1.1151 

14.3 
14.8 

14.9 

.2 

1.0205 

2.9 

•5 

1.0506 

6-9 

.8 

1.0821 

II.  0       1 

.1 

1.1158 

14.9 

•  3 

1.0209 

2-9 

.6 

1.0510 

7.0 

•9 

1.0828 

11.  0      I 

.2 

1-1163 

15- 

•4 

'  1.0213 

3-0 

•7 

1.0514 

7.05 

20.0 

1.0832 

II.  I 

•3 

i.  1168 

15- 

•5 

1.0217 

3-0 

.8 

1.0519 

7-1 

'.I 

1.0837 

II  .  I 

•4 

1.1172 

IS- 

.6 

I.  0221 

•9 

1.0^23 

7-2 

.2 

1.0841 

II.  2 

•  5 

1.1177 

IS- 

I.. 0225 

3-2 

13.0 

1.0527 

7-2 

•3 

1.0846    1 

II.  2 

.6 

i.  1382 

IS- 

g 

1.0229 

3-2 

.1 

1.0531 

7-3 

•4 

1.0850 

"•3 

.7 

.1187 

•9 

I-C233 

3-3 

.2 

1.0530 

7-3 

•5 

1.0855 

.8 

.1101 

15-3 

6.0 

1.0237 

3-3 

•3 

1.0540 

7-4 

.6 

1.0859 

11.4 

n-9 

.1196 

15-4 

.1 

I  .0241 

3-4 

•4 

1.0544 

7-4 

•7 

I  .0864 

11.45 

23.0 

.1201 

15.4 

.2 

1.0245 

3-4 

1.0548 

7-5    ! 

.8 

i.  0868 

II.  5 

.1 

.I2O6 

15-5 

•3 

•4 

1.0249 
1.0253 

1.0257 
1.0261 

Q         J 

•9 

1-0553 
1.0557 
I  .0561 
1.0566 

7-5      ! 
7-5 

7-65i 

.1 

.2 

I.  '0877 
1.0882 
1.0886 

11.  6 
II.  6     i 

11.7    I 
31.7 

.2 

•3 

•4 

.12IO 
.1215 
.I22J 
.1225 

15-  §5  ! 
15-6 
15-7 
5-7 

!? 

I  .  0265 

3-7 

14.0 

1.0570 

?7'l 

•3 

1.0891 

n.8      ! 

•b 

.1229 

5-8 

.8 

1.0269 

3-8 

.1 

i  0573 

7-8  ; 

•4 

1.0895 

11.  8     1 

•7 

•1234 

5-8 

•9 

I.C273 

3-8 

.2 

1.0^78 

7.9 

•5 

1.0900 

11.9 

.8 

.1239 

5-9 

7.0 

1.0277 
I  0281 

3-9 

3-9      1 

•3 
•4 

1.0583 
1.0587 

7-9 
8.0 

.0 

•  7 

I  .0904 
1.0909 

11.95 

12.0 

•9 
29.0 

•1244 

.1248 

K 

.2 

1.0286 

4-0      j 

•  5 

1.0391 

8.0 

.8 

1.0914 

12.05 

.1 

•1253 

16.0 

TABLE* 


117 


Per  cent,  of 
Sugar. 

il 

1 

'8 

!{! 

!| 

II 

ol 

Per  cent,  of 
Sugar. 

o  ^ 

II 

1 

•s 

§1 

r 

If 

II 

MM 

29.2 

.1258 

I6.I 

37-1 

i  .  1646 

20.35 

45-o 

.2056 

24.6 

52.9 

.2489 

28.7 

•3 
•4 

.1263 
.1267 

16.1 
16.2 

.2 

•  3 

1.1651 
1.1656 

20.4 
20.5 

.1 

.2 

.2001 
.2067 

24.6 
24-7 

53-0 

•2495 
.2500 

28.75 
28.8 

-5 

.12/2 

16.25 

•4 

1.1661 

20.5 

•  3 

.2O72 

24.7 

.2 

.2506 

28.85 

.6 

.1287 

16.3 
16.4 
16.4 

•7 

1.1666 
.1671 
.1676 

20.5 
20.6 

20.7 

•4 

:8 

ill 

24.8 
24.8 
24-9 

•3 
•4 
•  5 

.2512 
.2517 
.2523 

28.9 
28.9 
29.0 

•  9 

.1291 

16.5 

.8 

.1681 

20.7 

•  7 

^2093 

24-9 

.6 

•  2529 

29.1 

.1296 

16.5 

o'9 

.i6t5 

20.8 

.8 

.2099 

25.0 

•7 

•2534 

29.1 

•  i 

.2 

.1301 
.1306 

16.0 
16.6 

38.0 
.1 

.1692 
.1697 

20.8 
20.9 

46.0 

.2104 

.2110 

25.0 
25.1 

.8 

•9 

.2543 
.2546 

29.2 

29.2 

•  3 

.1311 

16.7 

.2 

.1702 

20.9 

.1 

.2115 

25-1 

54.0 

•2551 

29-3 

•4 

.1315 

16.7 

•3 

.1707 

21  0 

.2 

.2120 

25.2 

.1 

•2557 

29-3 

.1320 

16.8 

•4 

.1712 

21.05 

.3 

.2126 

25.2 

.2 

29.4 

•7 

.1325 
•1330 

16.85 
16.9 

.1717 

.1722 

21.1 

21.15 

•4 
•5 

•2136 

25-3 
25-35 

.3 

•  4 

•2574 

29-4 
29.5 

.8 
•9 

.1335 
.1340 

17-0 
17-0 

'I 

.1727 
•1732 

21.2 
21.3 

.6 
•  7 

.2142 
.2147 

25-4 

25-45 

:l 

.2580 
.2585 

29.5 
29.6 

31-0 

.1344 

17.1 

•9 

•1/37 

21-3 

.8 

•  2153 

25-5 

•  7 

.2551 

29.6 

.1 

•  1349 

I7-I 

39-0 

•1743 

21.4 

•9 

.2158 

25.6 

.8 

.2597 

29.7 

.2 

•  1354 

17.2 

.1 

.1748 

21.4 

47-0 

.2163 

25-6 

•9 

.2602 

29.7 

•3 

•1359 

17.2 

.2 

.1753 

21-5 

•  J 

.2169 

25-7 

55-o 

•  o5o8 

29.8 

•4 

•  1364 

17-3 

•3 

.17-16 

21.5 

.2 

•  2174 

25-7 

.2614 

29.8 

.5 

.1369 

•4 

.  1763 

21.6 

.3 

.2lbO 

25.8 

.2 

.2620 

29.9 

.5 

•1374 

17.4 

•5 

.1768 

21.6 

•4 

.2185 

25-8 

•3 

.2625 

29-9 

•  7 

•  137° 

17.4 

.6 

.1773 

21.7 

•  5 

.2191 

25-9 

•4 

.2631 

30-0 

.8 

.1383 

17-5 

•7 

1.  1778 

21  -I 

.6 

.2195 

25-9 

•5 

.2637 

30.05 

•9 

.I3&8 

17-55 

.8 

1.1784 

21.8 

.7 

.2201 

26.0 

.6 

.2642 

30.1 

32.0 

•1393 

17.6 

•9 

1.1789 

21.85 

.8 

.2207 

26.0 

•  7 

2648 

.1 

.1398 

17-7 

40.0 

1.1794 

21.9 

n 

.2212 

26.1 

.8 

•2654 

30-2 

.2 

.1403 

17.7 

.1 

1.1799 

22.0 

48.0 

.2218 

26.1 

•9 

.2660 

30-25 

-3 

1408 

178 

.2 

1.1804 

22.0 

.1 

.2223 

26.2 

56.0 

.2665 

30-3 

•4 

1412 

17.8 

•3 

.1809 

22.1 

.2 

.2229 

26.2 

.1 

.2671 

30.4 

-.5 

1417 

17.9 

•4 

.1815 

22.1 

•3 

.2234 

26.3 

.2 

.2677 

30.4 

.6 

1422 

17.9 

•5 

I  .  1820 

22.2 

•4 

.2240 

26.35 

•3 

.2683 

30-5 

•2 

1427 
1432 

18.0 
18.0 

.6 

.1825 
-1830 

22.2 
22.3 

•2245 
.2250 

26.4 
26.45 

.2688 
.2694 

30-5 
30-6 

•9 

1437 

18.  i 

.8 

•  1835 

22.3 

'.7 

.2256 

26.5 

.6 

.2700 

30.6 

33-0 
•  i 

1442 

14-17 

18.15 
18.2 

•9 
41.0 

.1840 
.1846 

22.4 
22.4 

.8 
•  9 

.2201 
.2267 

26.6 
26.6 

'.I 

.2706 
.2712 

30-7 
30-7 

.2 

1452 

18.25 

.1 

.1851 

22.5 

49-0 

.2272 

26.7 

•9 

.2717 

30-8 

•3 

1457 

18.3 

.2 

.1856 

22.C 

.1 

.2278 

26.7 

57-0 

•  2723 

30-8 

•4 
.5 

1462 
1466 

184 
18.4 

•3 
•4 

.1861 
.1866 

22.6 
22.65 

.2 

•3 

[2289 

26.1 

.1 

.2 

.2729 
•2735 

30-9 
30-9 

.6 

1471 
1476 

18.5 
18.5 

3 

.1872 
.1877 

22.7 
22.75 

•4 
.5 

.2294 
.2300 

26.9 
26.9 

•3 

•4 

.2740 
.2746 

31-0 
31-0 

.8 

1481 

18.6 

.7 

.1882 

22.8 

.5 

.2305 

27.0 

•  5 

.2752 

•9 

1486 

18.6 

.8 

.1887 

22.9 

.7 

•  23II 

27.0 

.6 

.27:8 

31  .  I 

34-0 

1491 

Ib.7 

•9 

.1,892 

22.9 

.8 

.2316 

27.1 

•  7 

.2764 

31-2 

1496 

18.7 

42.0 

.18^8 

23-0 

•  9 

.2322 

27.1 

.8 

.2769 

31-2 

.2 

1501 

18.8 

.1 

.1903 

23.0 

50.0 

.2327 

27.2 

•9 

•2775 

.3 

1506 

18.85 

.2 

.1908 

23.1 

.1 

27-2 

58.0 

.2781 

3^3 

•4 

1SH 

18.9 

•3 

•  1913 

23.1 

.2 

.2338 

27-3 

.1 

.2787 

.5 

1516 

18.95 

•4 

.1919 

23.2 

•  3 

-2344 

27-3 

.2 

.2793 

3M 

.6 

1521 

19.0 

•  5 

.1924 

23.2 

•4 

23-19 

27-4 

•3 

•2799 

31-5 

:l 

•  9 

1526 
1531 
1536 

19.1 
19.1 
19.2 

.6 

i 

.1929 
•1934 
.1940 

23  3 
23-3 
23-4 

.1 
•  7 

23S5 
2361 
2366 

27-45 
27-5 
27.55 

•4 

.2804 
.2810 
2816 

31-5 
gx.6 

31-6 

35-0 

1541 

19.2 

•9 

•1945 

23-45 

.8 

2372 

27.6 

•7 

2822 

3i-7 

.1 

1546 

19-3 

,43-0 

.19-0 

23-5 

•9 

2377 

27-7 

.8 

2828 

31.7 

.2 

•  3 

19-3 

19-4 

.1 

.2 

•19-5 
.1961 

23-55 
23-6 

51.0 
.1 

2J& 

27-7 
27.8 

•9 

59-o 

2834 
2840 

31.8 
31-85 

•4 

1561 

19.4 

.3 

.1966 

23-7 

.2 

2394 

27-8 

.1 

2845 

31.9 

.5 

1566 

19-5 

•4 

.1971 

23  7 

•  3 

2399 

27-9 

.2 

2851 

3i-95 

.6 
.7 

1571 
1576 

19.55 
19.6 

3 

.1976 
.1982 

23.8 
23-8 

•4 

.5 

2405 
2411 

27-9 
28.0 

•3 
•4 

iaSs 

32-0 
32.05 

.8 
•9 

ic,8i 
1586 

19.65 
19-7 

.1987 
.1992 

23-9 
23-9 

.6 
.7 

2422 

28.0 
28.1 

.1 

.'HIS 

32.1 
32-15 

36.0 
.1 

1591 
i  =,96 

19.8 
19.8 

•9 
44-0 

.1998 

.2003 

24.0 
24.0 

.8 
•9 

2427 
2433 

28.1 
28.2 

'.I 

2887 

32.2 
32-3 

.2 

xfoi 

19.9 

.1 

2008 

24.1 

52.0 

2439 

28.2 

•9 

.2893 

32-3 

•  3 

1606 

19.9 

.2 

.2013 

24.1 

.1 

2444 

28.3 

60.0 

2898 

32.4 

•4 

1611 

20.0 

•3 

.2019 

24.2 

.2 

2450 

28.3 

.1 

2904 

32.4 

1616 
1621 

20.0 
20.1 

.2024 

.2029 

24.2 
24-3  ! 

•4 

33 

28.4 
28.4 

.2 

•3 

2910 
2916  . 

32-5 
32.5 

!? 

t626 

20.1 

.8 

•  2035 

24-35 

•  5 

2467 

28.5 

•4 

2922 

32.6 

.8 

1631 

20  2 

.7 

.2040 

24.4 

.6 

2472 

28.5 

•5 

2928 

32.6 

•9 

1636 

20.  2 

.8 

.2045 

24-45 

.7 

2478 

28  6 

.6 

2934 

32.7 

37-o 

1641 

20.3 

•9 

.2051 

24-5 

.8 

2483 

28.65 

•  7 

2940 

32-7 

118 


DETERMINATION  *)F  SPECIFIC  GRAVITY. 


Per  cent,  of 
Sugar. 

11 
c/i  O 

Degree 
Baume. 

Per  cent,  of 
Sugar. 

II 

11 

Derree 
Baume. 

Per  cent,  of 
Sugar. 

if 

Degree 
Baume. 

1 

IPer  cent,  of 
Sugar. 

|| 

Degree 
Baume. 

§0.8 

.2946 

32-8 

67.2 

•3334 

36.0  j 

!  72-5 

.3732 

39-1 

79.8 

•4145 

42.2 

•9 

.29^2 

32.8 

.3 

•  334° 

36.0 

!  «6 

.3738 

39-1 

•9 

.4152 

42.2 

61.0 

.29^8 

32.9 

•4 

•  3346 

36-1  i 

•7 

•3745 

39-2 

80.0 

.4158 

42.2 

.1 

.2964 

32-9 

.5 

•  33^2 

36-1 

.8 

•3751 

39-2 

.1 

.4165 

42-3 

.2 

.2970 

33-o 

.6 

•3359 

36.2 

•9 

•3757 

39-3 

.2 

.4172 

42-3 

•  3 

•2975 

.7 

•3365 

36-2 

74.0 

•3764 

39-3 

•3 

.4179 

42-4 

•4 

.2981 

33-  i 

.8 

•3371 

36.3 

.1 

•3770 

39-4 

•4185 

42.4 

.2987 
•2993 

33-1 
33-2 

•9 

68.0 

•Ml 

36-3 
364 

.2 

•3 

•3777 
•3/83 

39-4 

39-5 

;| 

•  4192 
.4199 

42-5 
42.5 

i 

.2099 
.3005 

33-2 
33-3 

.1 

.2 

•3390 
•3396 

36.4 
36.5 

•4 
•  5 

•3790 
.3796 

39-5 
39-5 

'.I 

•4205 
.4212 

42.6 
42.6 

,  -9 

.3011 

33-3 

•  3 

.3402 

36.5 

.6 

•3803 

39-6 

'9 

.4219 

42-7 

62.0 

.3017 

33-4 

•4 

.3408 

36.6 

•  7 

.3809 

39-7 

81.0 

.4226 

42.7 

.1 

.2 

-30-3 
.3029 

33-4 
33-5 

J 

•34*5 

.  -3421 

36.6 
36.7 

.8 
•9 

.3816 
.3822 

39-7 
39-8 

.1 

.2 

.4232 
•  4239 

42.8 
42.8 

•3 

•3035 

33-5 

.7 

•3427 

36.7 

75.0 

.3828 

39.8 

•3 

.4246 

42-9 

•4 

•3041 

33-6 

.8 

•3433 

36.8 

.3835 

39-9 

•4 

•4253 

42-9 

•3047 

-3053 

33-6 
33-7 

69.0 

•3440 
•3446 

36.8 
36.9 

•  .2 

•3 

w 

39-9 
40.0 

3 

•4259 
.4266 

43-o 
43-0 

•7 

•30S9 

33-7 

.1 

•3452 

36.9 

•  4 

•3855 

40.0 

•7 

•4273 

43-1 

.8 

.3065 

33-8 

.2 

•3458 

37-0 

•5 

.3^61 

40.1 

.8 

.4280 

43-1 

•9 

.3071 

33-8 

.3 

•3465 

37-0 

.6 

.3868 

40.1 

•9 

•4287 

43-2 

63.0 

•3077 

33-9 

•4 

•3471 

37- 

•7 

•3^74 

40.2 

82.0 

•4293 

43-2 

.2 

•3ofc3 
.3089 

33-9 
34-0 

:i 

•3477 

•3484 

37- 
37- 

.8 
•9 

.3880 
.3887 

40.2 
40-3 

.1 

.2 

.4300 
•4307 

43-3 
43-3 

•3 

•3095 

34-0 

.7 

•3490 

37- 

76.0 

•3894 

40-3 

•3 

•4314 

43-4 

-4 

.3101 

34-1 

.8 

•3496 

37- 

.1 

•3900 

40.4 

-4 

•4320 

43-4 

•  5 

.3107 

34-i 

•9 

.3502 

37- 

.2 

•3907 

40.4 

•  5 

•4327 

43-5 

.6 

•3113 

34-2 

70.0 

37- 

•3 

.3913 

40.5 

.6 

•4334 

43-5 

3 

•3119 
•  3126 

34-2 
34-3 

.1 

.2 

•3515 
•3521 

37- 
37-5 

•4 
•5 

•3920 

.3926 

40.5 
40.6 

'.I 

•  4341 
•4348 

43-5 
43-§ 

•9 

•3132 

34-3 

•  3 

.3528 

.6 

•3933 

40.6 

•9 

•435.4 

43-6 

64.0 

•3138 

34-4 

•4 

•3534 

37  .8 

•  7 

•3940 

40.7 

83.0 

.4361 

43-7 

.1 

•3144 

34-4 

•5 

•3540 

37-6 

.8 

•3946 

40.7 

.1 

.4368 

43-7 

.2 

.3150 

34-5 

.6 

•3546 

37-7 

•9 

•3953 

40.8 

.2 

•4375 

43-8 

•3 
•4 

•3156 
•  3162 

34-5 
34-6 

3 

•3553 
•3559 

37-7 

77.0 
.1 

•3959 
.3966 

£:§ 

•3 

•4 

.4382 
-4388 

43-8 
43-9 

•5 

.3168 

34-6 

•9 

•3=65 

37-8 

.2 

•3972 

40-'9 

•5 

•4395 

43-9 

.8 

•3174 

34-7 

71.0 

•3572 

37-9 

•3 

•3979 

41. 

.8 

.4402 

44.0 

.7 

•  3180 

34-7 

.1 

•3^8 

P.  9 

•4 

•3980 

^I 

.7 

.4409 

44-0 

.8 

•  3186 

34:8 

.2 

•3585 

.0 

•5 

•3992 

41. 

.8 

.4410 

44-1 

•9 

.3192 

34-8 

•3 

38.0 

.6 

•3599 

41. 

•9 

•4423 

44-1 

65-0 

.3198 

34-9 

•4 

,3=.Q7 

38  i 

•  7 

.4005 

41. 

84.0 

•4430 

44-2 

.1 

.3205 

34-95 

•  5 

.3604 

ff  I 

.8 

.4012 

41. 

.1 

•4437 

44-2 

.2 

•32" 

35-o 

.6 

.3610 

382 

•9 

.4019 

41. 

.2 

•4443 

44-3 

•  3 

.3217 

35-05 

•  7 

.3616 

38.2 

78.0 

.4025 

•3 

•  4450 

44-3 

•4 

•3223 

35-1 

.8 

.3623 

38.2 

.1 

.4032 

41-3 

•4 

•4457 

44-3 

\ 

•3229 
•3235 

35-15 
35-2 

•9 

72.0 

.3629 
•3635 

38.3 
38.3 

.2 

•3 

•4039 
.4045 

41.4 
41.4 

.1 

.4464 
•4471 

44-4 
44-4 

•  7 

.3241 

35-25 

.1 

.3642 

38.4 

•4 

.4052 

41.5 

•7 

•4478 

44-S 

.8 

3247 

35-3 

.2 

.3b48 

38.4 

•5 

.4058 

41.5 

.8 

•4485 

44-5 

•  9 
66.0 

.3260 

35-35 
35-4 

•3 

•4 

:IP 

38.5 
38.5 

.5 
•7 

.4065 

.4072 

41.6 
41-6 

85.'? 

•4492 
.4498 

44.6 
44.6 

.1 

.3266 

35-4 

•5 

.3667 

38.6 

.8 

.4078 

41.7 

.1 

•4505 

44-7 

.2 

.3272 

35-5 

.8 

•3674 

38.6 

•9 

.4085 

41.7 

.2 

.4512 

44  7 

•3 

-4 

.3278 

•  3285 

35-5 
35-6 

;I 

.3680 

.3687 

38.7 
38.7 

79.0 
.1 

.4092 
.4098 

41.8 
41.8 

•3 

•4 

.4519 
•4526 

44-8 
44.8 

.5 

•3291 

35-6 

•9 

•3693 

38-8 

.2 

.4105 

41.9 

•4533 

44-9 

.6 

•3297 

35-7 

73-o 

•3699 

38.8 

•3 

.4112 

41.9 

•6 

•  4S40 

44-9 

.7 

•3303 

35-7 

.3705 

38.9 

•4 

.4119 

42.0 

.7 

•4547 

45-0 

.8 

•3309 

•3315 

35-8 
35-8 

.2 

•3 

•3712 
.3719 

38.9 
39-0 

3 

.4125 
.4132 

42.0 
42.1 

.8 

•4554 
.4561 

45-0 
45.1 

67!o 

.3322 

35-9 

•4 

•3725 

39-0 

.7 

.4138 

42.1 

86!o 

.4568 

45.1 

.1 

•3327 

35-0 

Another  table  is  given,  partially  supplementary  to  the 
last  and  calculated  by  the  same  formulas,  but  taking  in  a 
wider  range  of  densities,  and  having  the  degrees  Baume 
in  the  first  column: 


TABLE. 


119 


TABLE  SHOWING   RELATION   BETWEEN   DEGREES   BAUME,  PERCENTAGES,  AND 
SPECIFIC  GRAVITIES  OF  CANE-SUGAR  SOLUTIONS. 


en    • 

U 

. 

2-j 

8 

«• 

8-,-j 

OT 

!£ 

<ci- 

II 
&& 

gj 

3* 

11 

£o 

<u  a 

fl^ 

11 

cflO 

ga 

Sf3 

CM 

|l 

11 

cno 

ll 

1  * 

Is 

'<j"> 

0. 

.00 

.0000 

13- 

23.52 

1.0992 

26. 

47-73 

.2203 

39- 

73-23 

•  3714 

0.5 

.90 

.0035 

13-5 

24-43 

.1034 

26.5 

48.68 

.2255 

39-5 

74-25 

.3780 

I. 

1-5 

1.  80 

2.69 

.0070 
.0105 

14. 

14.5 

25-35 
26.27 

.1077 

.1120 

27. 

27.5 

49.63 
50.59 

.2308 
.2361 

40. 
40.5 

75.27. 
76.29 

.3846 
.3913 

2. 

3-59 

.0141 

15- 

.1163 

28. 

51-55 

.2414 

41. 

77-32 

•3981 

2.5 

3- 

4-49 
5-39 

.0177 
.0213 

15-5 
16. 

28.10 
29.03 

.I206 
.I25O 

28.5 
29. 

52.51 
53-47 

.2468 
.2522 

41.5 
42. 

78-35 
79-39 

.4118 

3-5 

6.29 

.0249 

16.5 

29.95 

.1294 

29.5 

54-44 

.2576 

42-5 

80.43 

.4187 

4- 

7.19 

.0286 

17- 

30.87 

•1339 

30. 

55-47 

.2632 

43- 

Si-47 

.4267 

4-5 

8.09 

.0323 

17-5 

31-79 

.1383 

30-5 

56-37 

.2687 

43-5 

82.51 

.4328 

5- 

9.00 

.0360 

18. 

32.72 

.1429 

31. 

57-34 

•2743 

44- 

83.  56 

.4400 

5-5 

9.00 

•0397 

18.5 

33-65 

.1474 

31-5 

58.32 

.2800 

44-5 

84.62 

.4472 

6. 

10.80 

•0435 

19. 

34-58 

.1520 

32- 

59-29 

.2857 

45- 

85.68 

•4545 

6.5 
7. 

11.70 

12.  6l 

•  0473 
.0511 

19-5 

20. 

35-50 
36.44 

.K66 

.l6l3 

32-5 
33- 

60.27 
61.25 

.2915 
•2973 

45-5 
46. 

86.74 
87.81 

.4619 
.4694 

i* 

I3-5I 
14.42 

•  OS!Q 
.0588 

20.5 
21. 

37-37 
38-30 

.1660 
.1707 

33-5 
34- 

62.23 
63.22 

•  3032 
.3091 

46.5 
47- 

88.81 
£9-96 

.4769 
.4845 

8.5 

15.32 

.0627 

i   21.  S 

39-24 

•1755 

34-5 

64.21 

•3151 

47-5 

91.03 

.4922 

9- 

16.23 

.0667 

1  22. 

40.17 

.1803 

35- 

f§'20 

.3211 

48. 

92.1.2 

.5000 

9-5 

17.14 

.0706 

22.5 

41.11 

.1852 

35-5 

66.19 

.3272 

48.5 

93.21 

.5079 

10. 

18  05 

.0746 

23. 

42.05 

.IQOI 

36. 

67.19 

•3333 

49- 

94.30 

5158 

10.5 

18.96 

.0787 

23-5 

42.99 

.I95O 

36.5 

68.19 

•3395 

49-5 

95.40 

.5238 

Ii. 

19.87 

0827 

24. 

43-94 

.2OOO 

37- 

69.19 

•3458 

50. 

P.« 

•5319 

ii.  5 

20.78 

.0868 

24.5 

44-88 

.2O50 

37-5 

70.20 

•3521 

50.5 

97.62 

.5401 

12. 

21.69 

.0909 

25- 

45-fcs 

I.2IOI 

3»- 

71.20 

.3S85 

5i- 

98-73 

.5484 

12.5 

22.60 

.0951 

25.5 

4^  7^ 

I.2I52 

38.5 

72.22 

•3649 

51-5 

99.85 

-55 

CHAPTER   VI. 


Determination  of  Cane-Sugar — Optical  Metliods. 


POLAEIZED    LIGHT. 


Fiff.7. 


By  Reflection. — When  a  ray  of 
light,  a  &,  Fig.  7,  falls  on  a  polished 
surface  of  glass  (wood,  ivory,  lea- 
ther, or  other  non-metallic  sub- 
stance), f  gJi  i,  inclined  to  it  at  an 
angle  of  35°  25',  it  is  reflected,  and 
the  reflected  ray  acquires  peculiar 
properties  whereby  it  is  said  to  be 
polarized.  The  change  which  has 
taken  place  in  the  light  may  be 
shown  as  follows  :  Let  the  polarized  ray  be  received  at  c  on 
a  second  reflecting  surface,  at  the  same  angle  as  before.  If 
the  surfaces  are  parallel  the  ray  is  reflected ;  but  if  the 
second  surface  is  caused  to  turn  around  c  &,  the  intensity 
of  the  ray  constantly  diminishes,  and  when  the  reflecting 
planes  are  perpendicular  to  each  other  no  light  is  reflected. 
If  the  rotation  of  the  upper  mirror  be  now  continued  the 
intensity  of  the  ray  gradually  increases,  and  attains  a 
maximum  when  the  surfaces  are  again  parallel.  If  the 
incident  ray  strikes  at  any  other  angle  than  that  given  the 
light  is  more  or  less  polarized ;  but  the  greatest  effect  for 
glass  is  always  obtained  under  the  condition  mentioned. 

The  angle  which  the  incident  ray  makes  with  the  normal 

120 


POLARIZATION  BY  REFRACTION.  121 

corresponds  to  the  greatest  effect  for  any  substance,  and  is 
called  the  polarizing  angle.  For  water  it  is  53°  11';  glass, 
54°  35';  air,  45°;  and  quartz,  57°  32'. 

By  Refraction. — The  phenomena  of  polarization  are 
exhibited  not  only  by  reflection,  but  also  by  refraction^ 
double  or  single.  All  doubly-refracting  crystals  have  the 
property  of  polarizing  light,  and  calc-spar  may  be  selected 
as  well  illustrating  this  fact.  When  a  ray  of  ordinary 
light  passes  through  a  crystal  of  calc-spar  in  any  direction 
except  that  of  the-  shorter  diagonal  of  the  rhomb,  which  is 
its  optical  axis,  it  is  divided  into  two  beams  of  equal  in- 
tensity, the  ordinary  and  the  extraordinary  ro,ys.  When 
the  ordinary  ray  passes  through  a  second  rhomb  of  spar  it 
again  experiences  double  refraction,  giving  rise  to  two 
beams  of  unequal  intensities.  If  the  second  crystal  be  ro- 
tated until  the  principal  planes  of  the  two  coincide — that 
is,  when  they  are  in  opposite  or  similar  positions — the  ordi- 
nary ray  acquires  its  greatest  intensity  and  the  extraordi- 
nary ray  disappears  ;  continuing  the  rotation,  the  extraor- 
dinary ray  reappears  and  increases  in  brightness,  while  the 
ordinary  beam  diminishes  until  the  principal  planes  are 
perpendicular.  When,  however,  the  extraordinary  ray 
suffers  a  second  refraction  by  means  of  calc-spar,  the  con- 
verse to  the  above  is  exhibited.  The  two  rays  resulting 
from  the  double  refraction  are  found  to  be  polarized. 

Among  other  crystalline  bodies  capable  of  polarizing 
light  by  double  refraction  may  be  mentioned  tourmaline 
and  selenite  (crystallized  sulphate  of  lime).  Glass  also,  sub- 
mitted to  strains  or  pressure,  becomes  doubly -refracting. 
The  plane  in  which  a  ray  of  polarized  light,  incident  at  the 
polarizing  angle,  is  reflected  or  transmitted  in  the  greatest 
degree,  is  called  the  plane  of  polarization  of  the  ray. 


122  DETERMINATION  OF  CANE-SUGAR, 

When  the  polarization  is  produced  by  reflection  the  plane 
of  polarization  is  identical  with  the  plane  of  reflection. 
Tlie  Nicliol  Prism. — A  valuable  device  for  producing 
polarized  light,  or  analyzing  it,  is  the  Nichol  prism,  which 
consists  of  a  rhomb  of  calc-spar  slit  along  the  plane  pass- 
ing through  the  shorter  diagonal,  and  having  the  two 
halves  cemented  together  again  by  Canada  balsam,  whose 
refractive  index  is  intermediate  between  the  ordinary  and 
extraordinary  indices  of  the  crystal.  Hence,  when  a  ray 
of  light,  S  C,  Fig.  8,  enters  the  prism, 
the  ordinary  ray  experiences  total 
/^reflection  on  the  surface  of  the  bal- 
sam,  a  &,  and  takes  the  direction 
C  d  O,  and  is  refracted  out  of  the  crystal ;  while  the  extra- 
ordinary ray,  C  e,  emerges  alone.  The  Mchol  prism  has 
the  advantages  of  perfect  transparency  and  a  very  com- 
plete polarizing  effect. 

Elliptical,  Circular,  and  Plane  Polarization. — In 
accordance  with  the  principles  of  the  undulatory  theory, 
when  the  ether  particles  that  make  up  a  beam  of  po- 
larized light  vibrate  in  parallel  straight  lines,  the  ray  is 
said  to  be  plane  polarized ;  when  the  particles  describe 
ellipses  around  their  positions  of  rest,  the  planes  of  the 
ellipses  being  perpendicular  to  the  ray  and  the  axes  paral- 
lel, the  light  is  eliiptically  polarized.  A  particular  case  of 
the  latter  is  when  the  axes  of  the  ellipses  become  parallel, 
when  circular  polarization  is  produced.  When  a  ray  of 
light  in  this  condition  is  refracted  by  a  Nichol  prism  and 
viewed  through  an  analyzer,  the  rotation  of  the  latter 
causes  no  change  in  the  intensity.  Circularly-polarized 
light  is  not,  however,  identical  with  ordinary  light,  as  may 
be  proved  by  the  interposition  of  a  plate  of  selenite  be- 


ROTATION  OF  THE  PLANE. 


123 


tween  the  polarizer  and  analyzer,  when  the  light  becomes 
elliptically  polarized. 

Rotation  of  the  Plane  of  Polarization. — Crystals 
of  quartz,  calc-spar,  and  tartaric  acid  can  cause  a  rotation 
of  the  polarization  plane  around  its  axis.  If  a  plate  of 
quartz,  cut  perpendicular  to  its  axis,  is  placed  between  the 
analyzer  and  polarizer,  color  is  exhibited,  the  tints  chang- 
ing in  the  order  of  the  colors  of  the  spectrum  as  the  ana- 
lyzer is  turned.  With  monochromatic  light  it  is  found  that 
when  the  prisms  are  adjusted  to  produce  total  extinction  of 
light,  and  the  quartz  introduced  in  the  path  of  the  ray, 
the  light  is  partially  restored,  but  that  on  rotating  the 
analyzer  again  total  extinction  is  produced.  The  angle 
through  which  it  is  necessary  to  turn  the  analyzer  to  pro- 
duce this  effect  represents  the  angular  rotation  which  the 
plane  of  polarization  has  experienced.  There  are  two  va- 
rieties of  quartz,  known  as  right  and  left  handed — the  one 
rotating  the  plane  of  polarization  to  the  right  and  the  other 
to  the  left.  Fig.  9  represents  the  rotation  of  the  plane  of 

Fig.9. 


polarization :  the  plane  A  B,  originally  perpendicular,  suf- 
fers successive  rotations  to  a  b,  a'  b',  and  a"  5",  the  angle 
C  W  a"  being  the  final  angle  of  rotation. 

Malus  has  established  the  following  laws  in  regard  to  ro- 
tatory polarization : 

I.  Tlie  amount  of  rotation  is  proportional  to  the  thick- 


124  DETERMINATION  OF  CANE-SUGAR. 

ness  of  tJie  quartz.  II.  The  rotation  of  tlie  plane  of 
polarization  varies  for  the  different  rays  of  the  spectrum, 
increasing  with  the  ref  Tangibility  of  the  light.  With  a 
plate  of  quartz  one  millimetre  thick  the  rotations  obtained 
for  different  colors  were  : 

Red 19°  Blue 32° 

Orange 21°  Indigo 36° 

Yellow 23°  Violet 41° 

Green 28° 

Specific  Rotatory  Power. — When  the  polarizer  and 
analyzer  are  so  placed  to  each  other  that  their  principal 
sections  are  parallel,  and  a  quartz  plate  3,75  mm.  thick  is 
interposed  in  the  path  of  the  polarized  ray,  a  peculiar  tint 
is  produced.  It  is  a  delicate  rose-purple,  but  changes 
quickly  into  red  or  violet  by  the  slightest  movement  in  the 
position  of  the  analyzer,  the  alteration  of  color  being  much 
more  rapid  and  decided  than  for  any  other  shade  or  color. 
It  is  called  the  transition  tint  (teinte  de  passage),  and  in 
measurements  of  the  rotative  power  of  various  bodies  this 
is  often  taken  as  a  standard.  The  rotatory  power  of  li- 
quids is  directly  as  the  length  of  the  column  through 
which  the  ray  passes,  and  also  as  the  quantity  of  active 
substance  dissolved,  if  it  is  a  solution.  If  e  be  the  amount 
of  substance  dissolved  in  a  unit  of  weight  of  the  solution, 
I  the  length  of  the  liquid  column,  and  a  the  observed  angle 
of  rotation  for  any  particular  color,  as  the  transition  tint, 

the  angle  of  rotation  for  the  unit  of  length  will  be  —  /  but, 

e  L 

as  the  solution  of  the  optically  active  body  is  often  attend- 
ed with  alteration  of  volume,  it  is  desirable,  in  order  to  ob- 
tain an  expression  independent  of  such  irregularities,  to 


SPECIFIC  ROTATORY  POWER.  125 

refer  the  observed  angle  of  deviation  to  a  hypothetical 
unit  of  density  —  that  is,  to  divide  the  quantity  —  by  the 

6     V 

density,  g,  of  the  solution.     The  expression  [a]  j  =  —  ^—  is 

e  L  g 

called  the  specific  rotatory  power,  and  represents  the  angle 
of  deviation  which  the  pure  substance,  in  a  column  of  the 
unit  of  length  and  density  1,  would  impart  to  the  ray  corre- 
sponding to  the  transition  tint.  For  instance,  a  solution 
containing  .155  gramme  of  cane-sugar  to  1  gramme  of  liquid 
has  a  specific  gravity  of  1.06,  and  deflects  the  polarized  ray 
for  the  transition  tint  24°  in  a  tube  20  mm.  long.  The  spe- 
cific rotatory  power  is,  therefore, 

•        '  [a]i=  ° 


55  X20X  1.06         '- 

[a]  is  the  expression  for  the  specific  rotatory  power  in 
general  ;  a  letter  affixed  shows  the  particular  ray  of  the 
spectrum  at  which  the  deviation  was  observed  :  thus,  [a]  D 
and  [a]  j  are  the  expressions  for  the  line  D  of  the  spec- 
trum, and  for  the  mean  yellow  ray,  or  transition  tint, 
respectively.  The  minus-  sign  is  prefixed  to  the  degree 
when  the  substance  rotates  to  the  left. 

The  Polariscope.  —  The  apparatus  for  determining  the 
rotatory  power  is  called  a  polariscope,  and  consists  of  an 
arrangement  carrying  two  JSTichol  prisms  properly  placed 
to  serve  as  analyzer  and  polarizer,  having  a  space  between 
them,  so  that  a  tube,  provided  with  glass  plates  at  its  ends 
and  filled  with  the  solution  to  be  examined,  may  be  inter- 
posed in  the  path  of  the  polarized  ray.  In  front  of  the  po- 
larizer is  inserted  a  quartz  plate  3.75  mm.  thick,  so  that 
when  the  prisms  are  adjusted  with  their  principal  planes 
parallel  the  transition  tint  is  visible.  The  interposition  of 


126  DETERMINATION  OF  CANE-SUGAR. 

the  active  substance  in  the  tube  causes  the  color  to  change, 
and  the  amount  of  rotation  of  the  analyzer  necessary  to  re- 
store the  transition  tint  measures  the  angle  of  rotation  of 
the  body  under  examination,  from  which,  with  the  data 
given,  the  specific  rotatory  power  may  be  calculated.  The 
instruments  to  be  described  furnish  more  elaborate  and  ac- 
curate means  of  determining  the  specific  rotatory  power. 

Many  organic  bodies  have  the  power  of  deviating  the 
plane  of  polarization.  Among  them  may  be  mentioned, 
DEVIATING  TO  THE  EIGHT,  cane-sugar,  dextrose,  milk- 
sugar,  dextrin,  camphor,  asparagine,  cinchonine,  quini- 
dine,  narcotine,  tartaric,  camphoric,  and  aspartic  acids, 
oil  of  lemons,  and  castor-oil ;  TO  THE  LEFT,  levulose,  starch, 
albumen,  amygdalin,  quinine,  nicotine,  strychnine,  brucine, 
morphine,  codeine,  malic  acid,  oil  of  turpentine,  and  oil  of 
valerian. 

Optical.  Saccharim  eters. — The  property  that  solu- 
tions of  cane-sugar  have  of  deviating  the  polarized  ray  in 
a  fixed  and  definite  degree  has  been  made  the  basis  of 
various  instruments  constructed  for  the  purpose  of  quan- 
titatively estimating  that  body.  These  instruments  are 
called  optical  saccTiarimeters,  polariscopes,  or  polarime- 
ters.  Those  treated  of  in  this  work  are  as  follows  :  Mit- 
scherlich's,  the  Soleil-Duboscq,  the  Soleil-Ventzke,  Wild's 
Polaristrobometer,  together  with  Duboscq's,  Laurents's, 
and  Schmidt  and  Haensch's  modifications  of  the  sacchari- 
metre  d  penombre  of  Jellett. 

MITSCHERLICH'S  SACCHARIMETER. 

This  instrument  consists  of  two  Mchol  prisms,  enclosed 
in  brass  tubes  supported  on  a  cast-iron  foot  by  means  of  a 
bar,  by  which  the  upper  part  may  be  made  to  slide  to  and 


MITSCHBELICH'S  INSTRUMENT. 


127 


fro  (Fig.  10).  The  tube  b  contains  the  polarizer,  and  it  may 
be  made  to  turn  on  its  axis,  being  kept  in  any  desired  posi- 
tion by  a  screw  at  I.  The  tube  a,  containing  the  analyzer, 
is  also  capable  of  rotating,  and  has  an  arm  attached,  as  well 
as  a  pointer  which  measures  the  amount  of  rotation  upon 
a  fixed  graduated  circle  of  brass.  The  graduation  of  the 
circle  is  in  degrees  from  0°  to  360°.  There  is  a  space  be- 


tween a  and  b  for  the  reception  of  the  tube  C,  which  is 
exactly  200  mm.  long  and  designed  to  hold  the  saccharine 
solution.  This  observation-tube  is  made  of  brass,  and 
closed  at  each  end  by  a  screw-cap  having  a  small  orifice  in 
its  centre  ;  glass  plates  are  placed  between  the  cap  and  the 
ground  ends  of  the  tube,  so  as  to  make  a  tight  joint  and 
to  allow  the  li£ht  to  pass  through  the  axis  of  the  tube. 

The  theory  of  the  apparatus  is  very  simple  :  the  light  en- 
tering by  the  first  prism  being  polarized,  on  passing  through 


128  DETERMINATION  OF  CANE-SUGAR; 

the  sugar  solution*  has  its  plane  deviated  to  the  right ;  the 
prisms  having  their  principal  sections  parallel,  it  becomes 
necessary  to  turn  the  analyzer  through  a  certain  angle  cor- 
responding to  the  strength  of  the  solution,  in  order  to  com- 
pensate for  the  rotatory  effect  of  the  sugar. 

To  adjust  the  instrument  for  use  it  is  important  to  fix 
correctly  the  zero-point,  and  that  on  the  scale  correspond- 
ing to  100  per  cent,  of  cane-sugar.  This  is  done  as  follows  : 

For  tlie  Zero — The  pointer  is  turned  to  0°  on  the  scale, 
a  gas  or  oil  lamp  being  placed  behind  the  apparatus  in  such 
a  position  that  the  light  may  shine  through  its  axis,  and 
the  observation-tube,  filled  with  water,  having  been  put  in 
place,  i  is  unscrewed  so  as  to  allow  the  tube  b  to  turn 
freely,  the  eye  being  placed  at  a.  If  the  apparatus  is  not 
set  correctly  at  the  time  of  observation,  a  colored  field  will 
be  seen,  and  the  tube  b  must  be  turned  until  the  field  gra- 
dually darkens  and  finally  presents  the  appearance  of  a 
round  disk  with  an  intense  vertical  black  band  in  the  cen- 
tre, gradually  shading  equally  on  both  sides  to  a  lighter 
tint,  and  appearing  dark  green  or  yellowish  at  the  extreme 
distance  from  the  centre.  When  the  field  presents  the 
above  appearance  the  rotation  of  the  tube  b  is  suspended, 
and  i  is  screwed  down  so  as  to  secure  it.  Now,  with  the 
apparatus  thus  set,  if  a  be  turned  by  means  of  the  index, 
the  field  becomes  gradually  lighter  until  the  pointer  indi- 
cates 90°,  when  it  is  at  its  maximum  brightness ;  if  the 
turning  be  continued  the  field  darkens  again,  and  at  180° 
it  presents  the  same  appearance  as  at  0°  ;  this  may  be  used 
as  a  control  experiment  for  the  correct  adjustment  of  the 
zero-point. 

If,  when  the  instrument  is  properly  adjusted,  and  the 
pointer  stands  at  0°  on  the  scale,  a  colorless  solution  of 


MITSCHERLICH'S  INSTRUMENT.  129 

cane-sugar  be  placed  in  the  observation-tnbe,  the  field  of 
the  saccharimeter  loses  its  dark  color  and  shows  a  yellow- 
ish tint,  owing  to  the  fact  that  the  plane  of  polarization  has 
been  altered  by  the  sugar  solution  ;  on  turning  the  analyzer 
in  a,  the  field  passes  through  a  series  of  chromatic  changes 
in  the  following  order:  yellow,  green,  blue,  violet,  red, 
orange.  To  adjust  the  point  corresponding  to  100 per  cent. 
of  sugar,  a  solution  of  15  grammes  pure,  dry  cane-sugar  is 
made  by  dissolving  in  water  and  diluting  to  100  c.c.;  this 
is  placed  in  the  tube  and  the  analyzer  turned.  The  field 
passes  through  a  series  of  colors  as  above  until  the  normal 
spectrum  of  the  apparatus  is  obtained,  which  presents  an 
appearance  as  follows — viz. :  the  right  half  of  the  colored 
circle  must  appear  of  a  pure  blue  ;  the  centre  has  a  line  of 
violet,  which  shades  oif  imperceptibly  into  red  on  the  left. 
If  the  instrument  correctly  indicates  at  the  point  for  100  per 
cent,  of  sugar,  the  above  appearance  of  the  field  is  seen 
when  the  index  of  the  scale  is  at  20°. 

Use  of  the  Instrument. — For  use  in  testing  saccha- 
rine products  15  grms.  is  taken,  dissolved  in  water,  and  di- 
luted to  100  c.c.  After  decolorization  with  lead  solution, 
and  filtering,  some  of  the  clear  solution  is  placed  in  the 
observation-tube,  and  the  analyzer  turned  by  means  of  the 
arm  attached,  until  the  normal  spectrum  is  obtained.  The 
reading  of  the  scale,  multiplied  by  five,  gives  the  percentage 
of  sugar.  It  is  evident  that,  when  the  degree  of  coloration 
of  the  material  to  be  tested  will  admit,  any  multiple  of  the 
normal  quantity  may  be  taken  and  the  solution  made  up  to 
100  c.c.  The  factor  for  multiplying  the  reading  will  be 
correspondingly  less.  With  weak  sugar  solutions  as  much 
as  75  grms.  may  be  weighed,  in  which  case  the  reading  of 
the  instrument  gives  directly  the  percentage. 


130  DETERMINATION  OF  CANE-SUGAR. 

Value  as  a  Saccharimeter. — The  chief,  and  indeed 
almost  fatal,  objection  to  the  Mitscherlich  apparatus  as  an 
instrument  of  precision  is  that,  in  the  majority  of  cases,  the 
actual  readings  of  the  scale  have  to  be  multiplied  by  a 
large  factor.  Owing  to  the  introduction  of  more  accurate 
polarizing  apparatus,  the  Mitscherlich  instrument  is  now 
comparatively  little  used. 

THE   SOLEIL-DTJBOSCQ  SACCHARIMETEE. 

Biot,  early  in  this  century,  investigated  the  principles  of 
circular  polarization,  and  especially  the  power  which 
quartz  plates  have  of  rotating  the  plane  of  polarized  light. 
He  constructed  the  polariscope  for  measuring  the  rotatory 
quality  of  various  substances,  which,  with  the  aid  of  cal- 
culation, was  capable  of  quantitatively  estimating  sugar. 

Clerget,  following  up  the  researches  of  Biot,  devised  a 
method  of  determining  cane-sugar  which  is  essentially 
that  now  employed  with  the  Soleil  saccharimeter.  The 
method  is  Clerget' s,  the  instrument  is  Soleil' s."*  The  appa- 
ratus has  been  improved  by  Duboscq,f  the  successor  of 
Soleil,  and  in  its  present  form  is  called  the  saccharimeter  of 
Soleil-Duboscq. 

Tlie  Instrument. — The  following  is  mainly  Terrell's 
excellent  description:  Figure  11  represents  the  appara- 
tus, which*  consists  of  two  metal  tubes  mounted  on  an 
appropriate  stand.  The  light  enters  at  H  by  a  circular 
opening  of  about  3  mm.  diameter,  and  traverses  the  achro' 
matic  polarizing  prism  P  ;  B,  is  a  plate  of  quartz,  called  the 
plate  of  double  rotation,  and  is  composed  of  two  halves  of 
equal  thickness,  cd,  cut  perpendicularly  to  the  axis  of 

*  Soleil,  Compt.  Rend ,  xxiv.  973.  f  Soleil  et  Duboscq,  ibid.,  xxxi.  248. 


THE  SOLEIL-DUBOSCQ. 


131 


crystallization  and  joined  together  so  that  the  line  of  sepa- 
ration is  vertical.  The  half-disks  have  contrary  rotations, 
the  one  being  left-handed  and  the  other  right-handed. 
The  light  passing  through  T  encounters'  Q,  a  quartz  plate, 
either  right  or  left  handed,  and  of  an  arbitrary  thickness. 
From  Q  the  ray  reaches  K  Kr,  which  are  two  wedge-shaped 

Fig.   ,,. 


quartz  plates,  having  the  same  kind  of  rotation,  but  differ- 
ent from  that  of  Q.  These  plates  are  each  fixed  in  a  brass 
slide  and  covered  with  plane  glass  plates  on  each  side  to 
protect  them  from  exterior  injury  or  displacement. 

By  means  of  a  rack- work  and  pinion,  to  which  is  fixed 
the  milled  head,  the  slides  may  be  made  to  move  to  and 

*  The  author  is  indebted  to  Dr.  II.  A.  Mott  for  the  above  enjjrmvinir. 


132  DETERMINATION  OF  CANE-SUGAR. 

fro  in  opposite  directions  while  remaining  parallel.  By 
this  arrangement,  at  will  the  thickness  of  "the  quartz 
through  which  the  polarized  ray  has  to  pass  may  be 
varied.  Finally  the  light  passes  to  the  analyzer  A  and 
the  quartz  plate  C.  The  small  Galilean  telescope  LL' 
serves  to  render  distinct  the  field  of  the  instrument.  The 
doubly-refracting  prism  A  is  so  placed  relatively  to  the 
diaphragm  of  the  telescope  that  the  passage  of  one  of  the 
rays  transmitted  by  the  polarizer  is  intercepted,  so  that  but 
one  passes,  either  the  ordinary  or  the  extraordinary  ray, 
according  as  the  plate  R  is  3.75  mm.  or  7.5  mm.  in  thick- 
ness. 

It  is  evident  from  the  construction  of  the  apx>aratus  that 
on  placing  the  eye  at  the  ocular,  S,  there  is  seen  the  ap- 
pearance of  a  luminous  disk  with  a  vertical  line  in  the 
middle,  produced  by  the  junction  of  the  quartz  plates  R. 
The  sum  of  the  thicknesses  of  the  two  prismatic  quartz 
plates  at  a  certain  relative  position  is  exactly  equal  to  that 
of  Q ;  and  hence,  as  the  rotations  are  in  different  senses, 
the  one  being  left  and  the  other  right  handed,  or  the  re- 
verse, it  follows  that  they  neutralize  each  other  and  pro- 
duce no  effect  on  the  polarized  ray.  On  looking  into  the 
instrument  when  thus  adjusted  it  will  be  seen  that  the  two 
half-disks  of  the  field  are  of  the  same  color.  If  now  we 
interpose  in  the  space  T  a  tube  containing  a  liquid  having 
a  rotatory  power,  immediately  the  uniformity  of  color  be- 
tween the  two  semi- disks  is  destroyed ;  this  is  due  to  the 
rotatory  effect  of  the  liquid,  which  destroys  the  mutual 
compensatory  effect  of  R  and  the  quartz  wedges.  For  ex- 
ample, if  the  solution  under  examination  consisted  of  cane- 
sugar,  the  deviation  would  be  to  the  right,  and  this,  with  that 
of  the  right-handed  plate  of  R,  produces  an  inequality  at- 


THE  SOLEIL-DUBOSCQ.  133 

tended  with  the  production  of  unequal  color^'the  field. 
The  field  may  be  restored  to  uniformity  by  turning  the 
screw,  thereby  increasing  or  decreasing  the  thickness  of 
the  quartz  at  K  and  compensating  for  the  deviating  effect 
of  the  liquid.  This  action  of  the  compensator  shows  not 
only  whether  the  solution  of  the  substance  examined  is 
right  or  left  rotating,  but  also  the  degree  as  measured  by 
the  thickness  of  quartz  necessary  to  neutralize  the  devia- 
tion of  the  body  examined.  The  latter  is  measured  by 
Fig.  1 2.  means  of  a  graduated  scale  fixed 

to  one  of  the  slides  B,  K/  (Fig.  12), 
while  upon  the  other  is  a  mark 
serving  as  an  indicator.  The 
scale  is  graduated  into  degrees 
indicating  percentages  of  sugar, 
on  each  side  of  the  zero.  A 
displacement  of  the  scale  equal 
to  one  division  is  equivalent  to 
a  rotative  effect  equivalent  to 
that  of  a  plate  of  quartz  yj-^  millimetre  thick. 

Soleil  greatly  improved  his  saccharimeter  by  placing  in 
front  of  the  ocular  of  the  telescope  a  Mchol  prism,  1ST  (Fig. 
11),  fixed  in  a  movable  case,  which  may  be  turned  at  will 
through  an  angle  of  180°.  This  arrangement  is  called  the 
producer  of  sensitive  tints.  The  prism  N  destroys  to  a 
great  extent  the  influence  of  the  coloration  in  the  liquids 
submitted  to  examination,  and  that  of  the  light  employed. 
It  also  permits  us  to  obtain,  by  adjusting  it  to  a  certain 
position,  the  sensitive  tint. 

The  tubes  designed  to  contain  the  liquids  to  be  tested 
consist  entirely  of  brass,  or  glass  enclosed  in  one  of  brass. 
The  extremities  of  the  tubes  are  ground,  so  as  to  be  per- 


134  DETERMINATION  OP  CANE-SUGAR, 

fectly  parallel  with  each  other  and  to  form  a  liquid-tight 
joint  with  the  glass  plates  that  cover  them.  Around  the 
ends  of  the  tubes  there  is  a  thread  cut,  by  which  brass 
caps,  perforated  in  the  centre,  may  be  screwed  on,  a  round 
plate  of  glass  having  been  previously  placed  upon  the  end. 
The  light  can  thus  pass  through  the  axis  of  the  tube  while 
it  is  filled  with  solution.  An  exterior  view  and  section  of 
these  tubes  may  be  seen  in  Fig.  13.  The  length  of  the 

Fig.  13- 


tubes  is  exactly  200  millimetres.  The  small  movable  tube 
containing  the  ocular  to  which  the  eye  is  placed,  can  be 
moved  so  as  to  adjust  the  focus  in  order  to  get  the  clearest 
view  of  the  field.  The  collar  on  the  ocular-tube,  y  (Fig. 
12),  which  is  connected  with  N,  enables  the  operator  to  ob- 
tain the  sensitive  tint  by  rotating  the  prism. 

Determination  of  the  Zero-Point. — For  this  pur- 
pose the  instrument  is  so  placed  that  the  light  traverses  its 
axis,  and  the  observation-tube  containing  distilled  water  is 
put  in  position,  as  T  in  Fig.  11.  The  telescope  is  then 
focussed  until  a  distinct  view  of  the  field  is  obtained.  If 
the  halves  of  the  disk  are  different  in  color  the  milled 
head  is  turned  either  to  the  right  or  left,  as  may  be  neces- 
sary, until  the  colors  appear  to  be  perfectly  identical  on 
either  side  of  the  vertical  line  when  the  observation  is 
.taken  ;  now  the  collar  near  the  ocular  is  turned,  and  it  will 


MANNER  OF  USING.  135 

be  perceived  that  the  color  of  the  field  changes  through 
red,  blue,  yellow,  etc.,  until  the  sensitive  tint  is  obtained, 
at  which  the  previously  appearing  uniformity  cf  the  field, 
may  be  seen  not  to  exist.  A  perfect  uniformity  may  be 
made  by  turning  the  milled' head  cautiously  again.  The 
color  of  the  sensitive  tint  varies  somewhat  with  different 
observers,  but  for  most  persons  it  is  the  rose-violet,  or 
where  the  lightest  color  of  the  spectrum  (almost  white) 
just  begins  to  verge  upon  the  red.  By  practising  these 
manipulations  the  operator  soon  becomes  skilled  in  the 
proper  adjustment  of  the  saccharimeter.  When  the  field 
presents  the  appearance  described,  the  zero  of  the  scale 
ought  to  coincide  with  the  indicator.  Should  this  not  be 
the  case  the  two  zeros  may  be  made  to  agree  by  turning 
the  screw-button  (Fig.  12),  placed  near  the  end  of  the 
scale. 

Manner  of  Using  the  Instrument. — To  use  the  sac- 
charimeter for  the  estimation  of  cane-sugar,  a  normal 
weight  of  16.19  grms.  is  taken,  dissolved  in  water,  and 
the  solution  diluted  up  to  100  c.c.,  being  suitably  deco- 
lorized. When  the  observation- tube  is  filled  with  a  so- 
lution thus  prepared,  and  is  placed  in  the  instrument 
previously  adjusted  so  that  the  field  appears  of  a  uni- 
form tint,  it  will  be  seen  that  the  uniformity  is  de- 
stroyed, and  that  the  half-disks  have  different  colors, 
one  being  complementary  to  the  other.  If  now  the 
milled  head  be  turned  until  the  equality  of  color  is  re- 
stored for  the  sensitive  tint,  the  number  of  the  scale  to 
which  the  indicator  points  shows  directly  the  percentage 
by  weight  of  cane-sugar  contained  in  the  material  ex- 
amined. 

A  new  instrument  should  be  tested  to  see  whether  it 


136  DETERMINATION  OF  CANE-SUGAR. 

makes  correct  indications  at  the  division  of  the  scale  read- 
ing 100  per  cent.,  and  whether  the  scale  is  correctly  gradu- 
ated, and  the  optical  portions  are  in  proper  condition  and 
adjustment.  16.19  grms.  of  pure,  dry  cane-sugar  are 
taken,  dissolved  in  water,  and  the  solution  made  up  to  100 
c.c.  This  constitutes  the  normal  solution  for  the  sacchari- 
meter, and  should  show  100°  on  the  scale,  the  zero-point 
having  been  adjusted  as  previously  described.  A  magni- 
fying-glass  accompanies  the  apparatus  to  assist  in  reading 
the  scale. 

Clerget's  Method  of  Inversion. 

The  readings  of  the  Soleil-Duboscq  saccharimeter  show 
directly  the  percentage  of  cane-sugar  when  no  other  opti- 
cally active  body  is  present.  Such  bodies  are,  however, 
often  found  in  saccharine  products  submitted  to  the  pola- 
riscopic  test,  particularly  in  beet  syrups  and  juice.  Under 
some  conditions  invert-sugar  may  also  have  a  similar  action, 
though  this  siigar  is  thought  to  be  without  action  on  the 
polarized  ray  when  occurring  in  commercial  saccharine 
products  (see  page  173). 

As  all  of  these  substances  have  a  specific  rotatory  power 
different  from  that  of  cane -sugar,  deviating  the  plane 
either  to  the  right  or  left,  it  follows  that  the  reading  of  the* 
saccharimeter  for  solutions  containing  such  bodies  must  be 
incorrect  as  indicating  cane-sugar,  and  the  error  will  be  in 
proportion  to  the  amount  of  optically-active  substance  pre- 
sent. 

Execution  of  the  Process. — Clerget  has  devised  a 
process  for  correcting  the  results  of  the  saccharimeter 
when  taken  on  solutions  containing  optically -active  invert- 


CLERGET'S  METHOD.  137 

sugar  besides  cane-sugar.*  The  direct  titre  is  taken  in  the 
ordinary  way,  and  a  part  of  the  solution  remaining  from 
this  estimation  is  filled  into  a  50  c.c.  flask  (which  is  gradu- 
ated to  50-55  c.c.)  up  to  the  50  c.c.  mark ;  then  concen- 
trated hydrochloric  acid  is  added  to  55  c.c.,  and  the  whole 
heated  on  a  water-bath  to  68°-75°  for  10  to  15  minutes. 
This  is  sufficient  to  produce  complete  inversion  of  the 
cane-sugar  present,  while  the  invert-sugar  is  unacted  on. 
After  the  liquid  in  the  flask  has  attained  the  temperature 
of  the  surrounding  air  it  is  placed  in  the  observation-tube 
and  the  reading  taken.  The  sugar  solution,  while  being 
heated  with  hydrochloric  acid>  is  apt  to  become  colored. 
The  color  can  be  readily  removed  by  shaking  the  cold 
liquid  with  a  very  little  bone-black.  The  observation-tube 
is  of  peculiar  construction.  It  is  larger  than  the  ordinary, 
lined  with  glass,  and  has  a  tubule  in  the  middle  for  the 
introduction  of  a  thermometer-bulb  in  order  to  take  the 

Fig    .4. 


temperature  of  the  .liquid  at  the  time  of  reading.    Fig.  14 
shows  the  arrangement. 

*  It  must  be  remembered  that  the  process  is  entirely  inapplicable  when  any 
optically-active  body  is  present  besides  cane  or  invert  sugar,  and  also  if  the  in- 
vert-sugar itself  exists  in  an  inactive  condition  as  regards  polarized  light. 


138  DETERMINATION  OF  CANE-SUGAR. 

The  tube  is  220  mm.  long,  the  increased  length  being  to 
allow  for  the  influence  upon  the  saccharimetric  reading 
made  by  the  dilution  of  10  per  cent,  on  the  addition  of 
acid. 

Calculation.— Clerget  found  that  a  solution  of  16.35 
grms.  pure  sugar  in  100  c.  c.  of  volume,  which  read  -\- 100° 
in  the  saccharimeter,  showed  after  inversion  a  rotation  of 
44°  to  the  left  at  zero  C. — a  difference  in  the  rotation  of  144, 
due  to  the  inversion.  The  optical  rotation  is  much  affect- 
ed by  the  temperature  of  the  solution  after  inversion,  to 
the  extent  that  the  deviation  diminishes  by  one-half  of  a 
degree  (very  nearly)  of  Soleil's  scale  for  each  degree  Centi- 
grade that  the  temperature  is  raised.  At  0°  C.  the  action 
is  expressed  by 

T°  =  144  -  J  T. 

If  S  represents  the  sum  or  difference  of  the  polariscopic 
readings  before  and  after  inversion,  T  the  temperature  of 
the  inverted  solution  when  polarized,  and  E.  the  percent- 
age of  cane-sugar  sought,  then 

144  —iT,:  100  ::  S  :  K, 
288  —  T  :  200  ::  S  :  B, ;  whence 
R_      200  S 

"  288  — T 

This  formula,  with  the  experimental  data,  will  enable  the 
operator  to  calculate  the  corrected  percentage  of  cane- 
sugar. 

Clerget's  Table.— To  save, the  trouble  of  this  calculation 
Clerget  has  given  a  table,  which  will  be  found  on  pages 
141,  142.*  Manner  of  Using  the  Table.—  When  a  liquid 

*  See  also  Tuchschmid,  Zeits.  /.  Rubenz.  Ind.,  1870,  649. 


CLERGET'S  PROCESS.  139 

is  tested  in  the  saccharimeter,  the  degree  of  the  scale  has 
to  be  multiplied  by  1.619  to  give  the  number  of  grammes 
in  a  litre.  This  calculation  the  columns  A  and  B  enable  us 
to  dispense  with.  By  finding  in  the  column  A  the  number 
of  the  scale  read,  the  one  corresponding  under  B  shows  the 
quantity  sought.  When  the  substance  is  submitted  to  in- 
version, the  sum  or  difference  *  of  the  direct  and  indirect 
readings  is  taken,  and  the  number  nearest  it  in  the  column 
corresponding  to  the  temperature  at  which  the  indirect 
reading  was  observed  is  sought.  The  horizontal  line  in 
which  this  number  occurs  is  followed  to  the  right,  the 
quantity  under  A  in  this  line  being  the  corrected  percent- 
age of  cane-sugar.  For  example : 

I.  Direct  reading,  -f-  38.7 
Indirect    "         -25    at  15°  C. 

Sum 63.7 

The  nearest  figure  to  the  sum  under  15°  is  64.1,  which  cor- 
responds to  47  per  cent,  of  sugar. 

II.  Direct  reading,  +  90 
Indirect    "        +  10  at  30°  C. 

Difference 80  =  62  per  cent,  sugar. 

When  the  sum  or  difference  does  not  correspond  exactly 
to  a  number  of  the  table  in  the  temperature  column,  the 
sugar  percentage  should  be  taken  for  that  next  below  and 

*  When  the  two  readings  are  in  the  same  sense — that  is,  both  plus  or  both 
minus— the  difference  is  taken ;  the  sum  is  taken  when  they  are  in  different 


14,0  DETERMINATION  OF  CANE-SUGAR. 

above,  and  the  average  of  two  taken— as  63.7  under  15°  C. 
is  nearest  to 

62.8,  corresponding  to  46  per  cent.,  and 
64.1,         "  "     47  per  cent. 


Average 46.5 

In  all  cases  the  results  are  calculated  more  exactly  with 
the  formula  than  by  the  table. 


CLERGET'S  METHOD. 


141 


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142 


DETERMINATION  OF  CANE-SUGAR. 


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g  s  8  1  o  rflH  S  a  a^a  a  §  a  222  f 


CLERGET'S  PROCESS.  143 

The  Method  applied  for  Saccharimeters  in  Gene- 
ral.—The  underlying  fact  of  Clerget's  process— namely, 
that  a  sugar  solution  reading  + 100°  will,  after  the  action 
of  acids,  show  —  44°,  making  a  difference  of  144°  due  to 
inversion — is  general,  and  hence  may  be  applied  to  the  re- 
sults of  any  saccharimeter.  By  the  following  method  of 
proceeding,  instead  of  the  one  described,  fully  as  accurate 
results  may  be  obtained  with  much  less  trouble,  and  only 
the  observation-tubes  used  in  ordinary  work.  The  direct 
reading  is  taken,  and  from  the  normal  solution  remaining 
50  c.c.  are  placed  in  a  flask  graduated  to  50-55  c.c.,  acid 
being  added  to  tl^e  upper  mark,  and  the  sugar  inverted  as 
previously  described.  After  inversion  the  solution  is  al- 
lowed to  cool,  the  evaporated  water  replaced,  and  the  read- 
ing taken  in  the  ordinary  glass  tube,  the  temperature  from 
a  thermometer  placed  near  the  saccharimeter  being  also 
observed.  The  reading  is  increased  by  ten  per  cent.  Care 
must  be  taken  to  keep  the  temperature  in  the  neighbor- 
hood of  the  instrument  as  uniform  as  possible,  and  to 
bring  the  solution  to  the  same  degree  before  filling  into  the 
tube.  If  these  precautions  are  taken  the  temperature  will 
not  vary  materially  during  the  observation.  The  calcula- 
tion is  the  same  as  that  already  given,  either  the  formula 
or  table  being  used. 


THE  SOLEIL-VENTZKE  SACCHARIMETER. 

This  instrument  differs  in  no  essential  from  the  one  last 
described,  though  the  mechanical  construction  has  been 
greatly  improved,  the  optical  parts  somewhat  changed  and 
arranged  in  a  different  manner.  These  improvements  are 


144  DETERMINATION  OF  CANE-SUGAR. 

due  to  Ventzke,*  and  later  to  Scheibler.f  This  sacchari- 
meter,  as  now  made  by  the  best  European  makers,:):  is  one 
of  the  most  practically  useful  for  the  optical  determination 
of  cane-sugar,  and  is  to  be  recommended  in  preference  to 
the  Soleil-Duboscq,  though  more  expensive.  Owing  to  its 
perfection  in  mechanical  construction  it  is  very  easy  to 
work  with,  and  in  regard  to  accuracy  leaves  nothing  to  be 
desired  for  all  technical  work. 


-n  ED 


Fig.  I5.a 

0 

i 

1    I 

D  " 

.  D 

c                                 D 

T 

1 
v— 

d 

~v  

E 

Description   of  the    Instrument. — Fig.   15a  shows 
the  arrangement  of  the  optical  portions : 

1.  A  is  the  regulator  for  changing  the  tints  of  the  double 
quartz  plates  C.     It  consists  of  the  Nichol  a,  and  a  quartz 
plate  &,  cut  perpendicular  to  the  axis  of  the  crystal,  both 
of  which  can  be  caused  to  rotate  by  appropriate  means. 

2.  B,  the  polarizer,  is  an  achromatic  calc-spar  prism. 
As  its  principal  section  is  vertical,  the  extraordinary  ray  is 
totally  reflected  at  the  axis,  and  only  the  ordinary  ray  is 
transmitted.    The  convex  surface  turned  towards  A  ren- 
ders the  rays  parallel. 

3.  The  double  quartz  plate  C  is  precisely  similar  to  that 

*  Ventzke,  Journ.  f.  PrJc.  Chemie,  xxv.  84,  xxviii.  3. 
]  Scheibler,  Zeitschrift  fur  Rubenz.,  1870.  609. 

J  Dr.  C.  Scheibler,  24  Alexandrinen  Str. ;  Schmidt  u.  Haensch,  4  Stall- 
schreiber  Str.,  Berlin. 


SOLEIL-VENTZKE  SACCHARIMETER.  145 

of  the  Soleil-Duboscq   apparatus.     Its  tMckness  may  be 
either  3.75  or  7.50  mm. 

4.  The  observation- tube,  D. 

5.  The    compensator,   E,   consists  of   the  right-handed 
plate  of  quartz  c,  and  the  wedge-form  plates  ^,  which  are 
of  left-handed  quartz,  one  of  which  is  fixed  and  the  other 
movable  by  means  of  a  rack  and  pinion,  to  increase  or  di- 
minish the  thickness  of  crystal  through  which  the  polar- 
ized ray  has  to  pass  ;  c  may  be  of  left-handed  quartz,  but 
in  that  case  the  optical  rotation  of  the  wedges  must  be  in  an 
opposite  sense. 

Fig.  ,5J. 


6.  The  analyzer,   F,   is  an  achromatic  calc-spar  prism, 
whose  principal  section  must  be  parallel  to  that  of  the 
polarizer,  B,  when  the  thickness  of  the  plate  C  is  3.75 
mm.,  or  perpendicular  to  it  when  the  latter  is  double  that 
thickness. 

7.  G  is  a  small  Galilean  telescope,  consisting  of  objective 
e  and  ocular  f. 

The  general  optical  theory  and  manner  of  working  with 
the  Soleil-Ventzke  is  the  same  as  that  of  the  Soleil-Bu- 
boscq,  and  the  reader  is  referred  to  the  description  of  that 


146  DETERMINATION  OF  CANE-SUGAR. 

instrument  for  these  particulars.  Only  to  points  where 
they  differ  will  particular  attention  be  paid  in  this  place. 
Fig.  15b  gives  a  complete  perspective  view  of  the  instru- 
ment with  the  latest  improvements  introduced  by  Scheib- 
ler.  A  brass  support  standing  on  an  iron  tripod  holds  the 
main  portion  of  the  apparatus,  the  middle  part  of  which 
consists  of  a  japanned  metal  receptacle,  7^,  for  the  observa- 
tion-tube, provided  with  a  hinged  cover,  which  serves  to 
shut  out  the  light  while  an  observation  is  taken.  At  one 
end  of  this  is  fixed  a  brass  tube  containing  the  double 
quartz  plate,  D,  and  the  polarizer,  C.  To  this  tube  is  fas- 
tened a  metal  case,  A  B,  arranged  so  as  to  be  capable  of  turn- 
ing freely  upon  its  axis,  and  which,  with  the  quartz  plate 
5  and  the  Mchol  a,  constitutes  the  regulator  (Fig.  15  a). 
The  regulator  is  rotated  by  a  toothed  wheel  attached  to  it, 
actuating  in  a  pinion  fastened  to  a  rod  which  terminates  at 
the  front  of  the  instrument  in  a  milled  head,  L,  where  it 
can  be  conveniently  reached  by  the  operator.  At  G  is  the 
compensator,  and  F  E  are  the  quartz  wedges,  each  of  which 
is  secured  in  a  strong  brass  frame  and  covered  with  parallel 
plates  of  glass  on  each  side  ;  F  is  fixed  by  two  screws  and 
carries  the  vernier,  while  E  can  move  horizontally  by 
means  of  a  toothed  rack  on  the  lower  portion  of  the  brass 
frame,  and  a  pinion  moved  by  the  milled  head  M ;  E  carries 
the  scale,  which  is  graduated  on  both  sides  of  zero.  The 
scale  and  vernier  are  not  shown  in  the  plate  ;  the  latter 
reads  to  tenths  of  one  per  cent.  In  order  to  read  the 
scale,  a  horizontally-placed  telescope,  K,  is  screwed  on  to 
the  apparatus,  and  the  light  from  the  scale  is  reflected  into 
it  by  the  mirror,  S.  The  analyzer  may  be  turned  by  a 
key,  so  that  it  can  be  put  into  proper  relation  to  the  po- 
larizer, if  necessary.  The  key  also  may  be  used  to  adjust 


SOLEIL-VENTZKE  SACCHARIMETER.  147 

tlie  zero  of  the  scale  to  that  of  the  vernier  by  means  of  a 
screw  in  F  not  shown  in  the  plate. 

Adjustment  of  Prisms.— If,  by  any  cause,  the  ana- 
lyzer and  polarizer  are  not  in  perfect  adjustment  towards 
each  other,  which  is  shown  by  the  fact  that  for  any  posi- 
tion of  the  plates  F  E  there  is  no  equality  of  tint  on  both 
sides  of  the  vertical  line  in  the  field  of  the  apparatus, 
the  adjustment  must  be  made.  For  this  purpose  E  is  re- 
moved by  turning  M  until  it  can  be  taken  out ;  then  the 
screws  that  hold  F  are  unscrewed,  and  this  plate  also 
removed ;  and  finally  the  compensation-plate  is  dis- 
placed. Now,  with  the  cover  closed,  an  observation  is 
taken,  and,  by  means  of  the  key,  H  is  turned  until  the 
field  gives  the  normal  spectrum  ;  the  key  is  then  taken  out 
and  the  parts  replaced  as  they  were  before.  Finally,  the 
zero  of  the  vernier  is  adjusted  to  correspond  to  that  of  the 
scale  by  an  observation  taken  with  an  empty  tube,  by 
turning  the  screw  on  F  by  means  of  the  key.  When  the 
apparatus  is  thus  adjusted  it  will  give  correct  indications 
for  all  points  of  the  scale,  provided  the  latter  is  equally  di- 
vided, and  the  instrument  is  not  essentially  faulty  in  con- 
struction. 

On  the  scale  of  the  original  Soleil-Ventzke  saccharimeter 
a  solution  of  pure  cane-sugar  of  a  density  1.10  at  17j-°  C., 
observed  in  a  tube  200  mm.  long,  reads  100°.  It  has  been 
experimentally  proved  that  such  a  solution  contains  26.048 
grms.  cane-sugar  in  100  c.c.  Hence,  if  26.048  grms.  of 
sugar  be  weighed,  dissolved  in  water,  and  the  solution  di- 
luted to  100  c.c.,  the  result,  as  read  in  the  saccharimeter, 
would  be  the  same  as  if  the  solution  were  prepared  of 
the  normal  density.  Ventzke  used  a  special  areometer 
(page.  106),  giving  the  densities  required  with  great  ac- 


148  DETERMINATION  OF  CANE-SUGAR. 

curacy.  The  method  of  direct  weighing  the  normal  quan- 
tity is  now  used  altogether  in  place  of  the  earlier  one  with 
the  areometer. 

Method  of  Using  the  Apparatus.— The  material  to 
be  tested  is  weighed  in  a  tared  dish  provided  with  a  coun- 
terpoise. Any  balance  will  serve  that  weighs  quickly 
and  accurately  to  .010  grm.,  as  an  error  of  this  quantity 
makes  a  difference  in  the  reading  of  less  than  ^  of  one  de- 
gree on  the  scale.  The  observation-tubes  are  of  glass, 
respectively  200  and  100  mm.  long,  furnished  with  screw- 
caps  and  glass  plates  to  close  the  ends  (page  134).  Glass 
tubes  are  objectionable  not  only  on  account  of  their  fragili- 
ty, but  also  because  the  brass  screw-threads  at  the  end  fre- 
quently become  loose,  the  effect  of  which  is  to  lengthen 
unduly  the  column  of  liquid  under  observation,  rendering 
the  reading  too  high.  A  brass  tube  of  the  same  form 
and  dimensions  may  be  used  with  great  convenience.  The 
only  objection  which  can  be  urged  against  the  latter  is  that 
the  coefficient  of  the  linear  expansion  of  brass  is  greater 
than  that  of  glass,  and  consequently  variations  of  tempe- 
rature in  altering  the  length  of  the  tube  would  give  rise  to 
error.  This  objection  is,  however,  not  well  founded,  as  it 
can  be  proved  by  calculation  that  in  the  most  extreme 
cases  the  maximum  error  for  a  tube  200  mm.  long  corre- 
sponds to  less  than  .04  per  cent,  sugar. 

The  shorter  tube  (100  mm.)  should  only  be  used  when  it 
is  impossible  or  inconvenient  to  get  a  solution  light  enough 
to  read  in  the  longer  one.  When  the  readings  are  taken 
with  the  former  they  are  to  be  doubled  to  make  them  indi- 
cate percentages  of  sugar. 

To  Test  the  Correctness  of  the  Saccharimeter.— 
When  a  new  saccharimeter  is  obtained,  or  the  operator  uses 


SOLEIL-VENTZKE  SACCHAEIMETEK.  149 

one  with  whose  antecedents  he  is  not  familiar,  it  should  be 
thoroughly  examined.  First  the  observation-tubes  should 
be  measured  with  care  to  see  whether  they  are  of  standard 
length.  For  this  purpose  a  reliable  metal  or  ivory  rule 
should  be  procured,  graduated  into  millimetres.  The  tube 
may  be  measured  by  a  pair  of  accurate  calipers,  which 
should  be  perfectly  adjusted  to  the  ends  of  the  tube,  and 
then  applied  to  the  standard  rule.  If  after  several  trials 
the  tube  is  found  to  be  too  long,  it  must  be  ground  down 
to  the  right  length  with  oil  and  emery  on  a  thick  glass 
plate  ;  if,  on  the  other  hand,  it  is  too  short,  it  must  be  re- 
jected, or  a  correction  made  for  the  readings  taken  with  it 
as  follows :  Suppose,  for  example,  a  tube  measured  199 
mm. ;  as  the  readings  of  the  saccharimeter  are  directly  pro- 
portional to  the  length  of  the  column  of  saccharine  liquid, 
and  200  mm.  corresponds  to  100°,  we  have 

200  :  199  :  :  100  :  x  =  99.5°. 

The  various  adjustments  for  the  zero  and  100°  point  of 
the  scale  are  made  in  an  entirely  similar  manner  to  those 
for  the  Soleil-Duboscq  saccharimeter ;  it  is  to  be  under- 
stood that  before  the  adjustment  at  0°  is  made  it  has 
been  ascertained  whether  the  analyzer  and  polarizer  are  in 
proper  relation,  and  if  they  are  not  they  must  be  corrected 
according  to  the  directions  already  given.  The  100°  point 
of  the  scale  is  tested  by  dissolving  26.048  grammes  of  pure 
cane-sugar  in  water,  diluting  to  100  c.c.,  and  taking  a  care- 
ful observation  with  the  solution  thus  obtained  in  the  100 
mm.  and  200  mm.  tubes  ;  their  readings  should  be  exactly  50° 
and  100°  respectively.  The  correctness  of  the  division  of 
the  scale  is  best  tested  in  the  laboratory  by  weighing  inde- 
finite quantities  of  pure  sugar,  less  than  the  normal  weight, 


150  DETERMINATION  OF  CANE-SUGAR. 

dissolving  in  water,  diluting  to  100  c.c.,  and  polarizing— 
thus,  if  20.50  grammes  of  sugar  are  taken,  then 

26.05  :  20.5  :  :  100  :  x 

20.5  X  100      7ft  7 
-26.05-  =  78'7' 

which  is  the  division  of  the  scale  that  the  solution  should 
indicate.  If  the  indications  for  various  points  are  different 
from  those  which  the  amounts  of  sugar  taken  should  give, 
while  the  0°  and  100°  point  is  correct,  the  scale  is  not  pro- 
perly divided ;  if  the  error  exists  to  any  considerable  ex- 
tent, and  at  different  parts  of  the  scale,  the  instrument 
should  be  rejected,  or  a  new  scale  obtained  for  it.  Schei- 
bler  *  has  given  a  method  for  correcting  the  scale,  which  he 
calls  the  "  Hundert  Polarisation"  and  which  consists  in 
first  obtaining  the  polarization  of  a  raw  sugar  or  other  sac- 
charine material,  and  then  calculating  the  amount  neces- 
sary to  be  weighed  to  polarize  100  ;  as,  for  example,  a  sugar 

polarizing  85  would  require  26'05  ?:  1QO  =  30.65  grammes 

oO 

to  be  taken  for  the  test  to  show  a  saccharimetric  reading  of 
100.  If  a  number  of  points  on  the  scale,  distributed  from  0° 
to  100°,  are  found  to  be  correct,  the  saccharimeter  may  be 
accepted  as  reliable.  The  troublesome  operation  of  pre- 
paring pure  sugar  and  making  solutions  of  different 
strengths  to  test  the  correctness  of  the  scale  may  be  dis- 
pensed with  by  employing  quartz  plates  of  various  thick- 
nesses, and  consequently  whose  rotatory  powers  corre- 
spond to  sugar  solution  of  different  strengths.  Such  plates 
are  made  by  Dr.  Scheibler,  of  Berlin,  for  use  on  almost 
every  part  of  the  scale  from  38°  to  100° ;  it  is  only  neces- 

*  Zeits.  f.  ZucJcerfabr.  des  deutsoh.  JKeiches,  xxi.  320. 


SOURCE  OF  LIGHT. 


151 


sary  to  place  them  in  the  end  of  the  observation-tube  and 
to  proceed  as  if  a  sugar  solution  was  to  be  examined. 

Source  of  Light. — The  source  of 
light  for  use  with  this  and  other  sac- 
charimeters  not  requiring  the  mono- 
chromatic flame  may  be  either  a  good 
Argand  oil-lamp  such  as  shown  in 
Fig.  16,  or  an  ordinary  Argand  gas- 
burner. 

A  saccharimeter  is  best  mounted 
for  laboratory  work  in  a  wooden  case 
of  suitable  dimensions,  placed  in  the 
darkest  part  of  the  room  and  sup- 
ported on  brackets,  or  in  any  other 
way.  The  end  of  the  polariscope 
should  be  placed  at  least  six  centi- 
metres from  the  source  of  light  to 
avoid  the  danger  of  softening  the 

cement  used  in  keeping  the  prisms  of  the  apparatus  in  place. 
The  case  intended  for  the  reception  of  the  instrument  may 
have  a  hinged  top  that  can  be  thrown  back  when  the  appa- 
ratus is  in  use,  and  also  a  door  in  front  provided  with  a 
lock  and  key.  A  very  convenient  arrangement  for  the  re- 
gulation of  the  light  is  to  have  an  Argand  gas-burner 
with  a  switch,  to  which  is  attached,  by  a  wire  link,  a  brass 
or  iron  rod  made  of  stout  wire,  which  passes  through  the 
front  of  the  case,  terminating  on  the  outside  in  a  knob  ; 
when  the  polariscope  is  to  be  used  for  a  series  of  observa- 
tions, the  gas-cock  may  be  turned  on  full,  and  then  the 
flame  regulated,  according  to  the  requirements  of  the  work, 
by  means  of  the  rod  attached  to  the  switch  of  the  burner, 
by  pulling  it  in  or  out  according  to  the  size  flame  desired. 


152  DETERMINATION  OF  CANE-SUGAR. 

The  screw-caps  of  the  observation-tube  must  not  press 
too  strongly  upon  the  glass  plates,  as  glass  submitted  to 
strains  or  pressure  becomes  capable  of  polarizing ;  rubber 
washers  should  be  interposed  between  caps  and  plates. 

WILD' S    POLAKISTEOBOMETEE. 

This  instrument  was  invented  in  1864  by  H.  Wild.*    A 

Fig.  .7. 


striking  peculiarity  of  it  is,  that  between  the  polarizing  and 
analyzing  Nichols,  of  which  the  first  rotates,  is  interposed 
a  Savart's  polariscope,  by  which  a  number  of  black  bands 
of  interference  are  produced,  which  disappear  for  a  known 
position  of  the  polarizer  ;  this  position,  which  can  be  deter- 
mined with  great  precision,  forms  the  stopping-point  (merTc- 
maT)  for  the  operator.  The  light  used  is  that  of  the  sodium 
flame. 

Description  of  the  Instrument. — Two  views  are  given 
in  Figs.  17  and  18  ;  the  capital  letters  in  one  correspond  to 
the  small  letters  of  the  other.  Upon  a  metallic  standard,  X, 
Fig.  18,  is  carried  a  brass  frame,  Y,  at  either  end  of  which 
are  the  polarizing  and  analyzing  arrangements ;  the  light 
enters  at  &,  Fig.  17,  through  a  round  diaphragm,  c,  and 

*  H.  Wild,  Ueber  ein  neues  Polaristrobometer.     Berne,  1865. 


WILD'S  POLARISTROBOMETER. 


153 


passes  to  the  JSTichol  prism  d,  which  is  joined  to  the  scale  e, 
and  turns  with  it.  The  polarized  ray  passes  through  the  ob- 
servation-tube and  arrives  at  the  ocular  of  the  polariscope. 
This  part  of  the  apparatus  produces  the  phenomena  of  in- 
terference, and  consists  of  two  plates,  <?,  of  calc-spar  three 
millimetres  thick,  cut  at  an  angle  of  45°  to  their  optical 

Fig.  .8. 


T 


axes  and  cemented  together  again,  so  that  their  principal 
sections  are  at  right  angles  to  each  other ;  there  is  a  small 
telescope,  magnifying  about  five  times,  whose  lenses  are 
shown  at  h  and  i.  Between  these,  and  in  the  focus  of  7i,  is 
a  round  diaphragm  four  millimetres  in  diameter  and  con- 
taining cross-wires.  Finally  the  analyzing  Mchol  Z,  which 
is  fixed,  has  its  principal  section  horizontal ;  with  the  latter 
the  crossed  principal  sections  of  the  plate  g  must  form  an 


154 


DETERMINATION  OF  CANE-SUGAR. 


angle  of  45°.     At  m  m  is  a  wide  slit,  which  by  the  screws 
may  be  altered  in  size,  serving  to  adjust  the  zero-point 

of  the  instrument.  In  order  that 
the  relative  position  of  the  parts 
g  and  I  should  remain  unchanged, 
the  ocular-tube,  in  which  is  con- 
tained the  Mchol  prism  and  the 
lens,  is  fastened  by  a  pin  and  a 
slot,  as  shown  in  the  Fig.  18.  The 
whole  polariscope  is  contained  in 
the  tube  Z,  arranged  so  that  it  can 
rotate  through  a  small  angle  ;  IS"  is 
a  shield  to  protect  the  eye  from 
the  light.  In  the  rotation  of  the 
polarizing  prism,  the  brass  plate 
on  which  is  engraved  the  scale 
rotates  also ;  this  movement  is 
effected  by  the  rod  P  Q.  The 
fixed  index,  r,  serves  to  show 
the  amount  of  the  rotation.  For 
reading  the  divisions  of  the  scale 
the  telescope  s  is  provided,  at  the 
end  of  which  is  an  opening,  V, 
with  a  mirror  which  throws  the 
light  of  a  small  gas  flame  on  the 
scale.  The  source  of  light  is  the 
sodium  flame,  consisting  of  a  Bunsen  burner  or  alcohol 
lamp  in  which  is  kept  a  small  globule  of  chloride  of  sodium 
fused  on  a  platinum  wire.  Laurent's  monochromatic  lamp 
is  an  excellent  arrangement  for  producing  the  sodium  flame, 
and  may  be  used  for  any  saccharimeter  requiring  that  kind 
of  illumination.  It  consists  (Fig.  19J)  of  a  vertical  Bunsen 


WILD'S  INSTRUMENT. 


155 


burner,  a,  surmounted  by  a  chimney,  b;  d  rotates  and  car- 
ries a  fine  platinum  wire  on  which  is  fused  some  sodium 
chloride  or  carbonate,  c. 

The  Use  of  the  Apparatus.— For  the  execution  of  an 
observation  the  empty  tube  is  placed  in  the  apparatus,  and 
the  ocular  of  the  polariscope,  by  the  screws  m  m,  is  opened 
wide  enough  to  admit  of  a  clear  view  of  the  cross-wires. 
Turning  the  polarizer  by  means  of  p,  Fig.  17,  we  find  such 
a  position  that  the  illuminated  field  shows  a  number  of 
parallel  black  lines  or  fringes,  as  in  Fig.  19,  a. 

By  continuing  the  rotation  there  arrives  prg.  \g. 

a  time  when  a  clear  portion,  free  from 
fringes,  appears  on  the  field,  and  we  can, 
by  moving  the  button  p  to  and  fro,  distri- 
bute the  fringe-free  portion  symmetrically 
on  the  field  with  reference  to  the  cross- 
wires,  as  shown  by  Fig.  19,  b.  This  appear- 
ance serves  as  a  stopping-point  for  the  ope- 
ration, and  the  reading  of  the  scale  should 
be  0°  if  all  adjustments  are  correct.  If  the 
polarizing  Mchol  be  turned  still  further, 
the  fringes  again  increase  in  intensity,  and  finally  become 
faint  once  more,  the  field  presenting  the  same  appearance 
at  90°,  180°,  and  270°  as  it  did  at  zero.  The  reading  may 
be  made  at  all  of  these  points,  and  the  results  should 
agree.  The  disappearance  of  the  fringes  corresponds  to  a 
position  of  the  rotating  prism,  when  its  principal  section 
coincides  with,  or  is  at  right  angles  to,  that  of  the  first  plate 
of  the  calc-spar  prism  g.  The  greatest  intensity  of  the 
fringes  is  observed  when  they  are  inclined  at  an  angle  of 
45°. 

If,  after  the  zero-point  of  the  scale  has  been  sufficiently 


156  DETERMINATION  OF  CANE-SUGAR. 

verified,  the  observation-tube  is  filled  with  an  optically 
active  solution,  the  fringes  of  interference  appear  again, 
and  the  polarizer  is  then  turned  until,  after  several  trials, 
the  field  presents  the  appearance  shown  in  Fig.  10,  b. 
When  this  point  is  attained  the  rotation  is  suspended,  and 
the  reading  corresponding  to  the  amount  of  sugar  in  the 
solution  is  taken. 

This  description  of  the  polaristrobometer  has  reference 
to  the  apparatus  with  a  circular  scale  divided  into  degrees 
from  0  to  360.  A  sugar  scale  has  been  added  by  dividing 
this  into  four  hundred  equal  parts. 

To  estimate  the  sugar  in  a  saccharine  product  20  grms.  are 
weighed  and  dissolved  to  100  c.c.,  or  10  grms.  to  50  c.c., 
and  the  observation  taken  in  the  200  mm.  tube.  The  read- 
ing is  to  be  halved  to  show  percentages  of  sugar.  Where 
the  assay  contains  but  a  small  amount  of  sugar  forty  or 
sixty  grammes  may  be  weighed,  dissolved  to  100  c.c.,  and 
the  result  divided  by  four  or  six,  as  the  case  may  be. 

SHADOW  SACCHARIMETERS 

(SaccJiarimetre  d  penombre). 

A  distinguishing  peculiarity  of  this  class  of  saccharime- 
ters  is  that  for  a  certain  position  of  the  optical  parts  the 
field  of  the  instrument  appears  divided  into  two  halves, 
the  one  very  bright  and  the  other  as  dark.  For  another 
position  the  whole  field  assumes  a  uniform  grayish  shadow, 
without  any  trace  of  vertical  line. 

To  Prof.  Jellett,  of  Dublin,  belongs  the  credit  of  first 
inventing  an  instrument  of  this  kind,  though  it  has  been 
much  improved  by  the  labors  of  Dubosccj  and  Cornu.  The 
source  of  light  is  monochromatic. 


SHADOW  SACCHAEIMETEBS: 


157 


DUBOSCQ'S  SACCHAEIMETRE  A  PETTOMBKE. 
Fig.  20  shows  the  apparatus  devised  by  Duboscq  and 

Fig.  20. 


Cornu.  The  polarizing  prism  is  of  peculiar  construction. 
A  rhomb  of  calc-spar  is  divided  longitudinally,  following 
the  plane  of  the  smaller  diagonal  A  B,  F!g.2,. 

Fig.  21,  and  each  of  the  cut  faces  are 
removed  for  an  angle  of  two  and  a  half 
degrees,  the  sections  i  A  B  and  A  B  o 
being  taken  off  ;  the  remaining  parts  are  M 
cemented  together  again  on  the  planes 
passing  through  B  i  and  Bo.  A  double 
prism  is  thus  obtained,  of  which  the 
principal  sections  are  at  an  angle  of  5°.  Owing  to  this  con- 
struction, for  very  small  changes  in  the  luminous  field  a 
comparatively  large  angular  rotation  of  the  analyzer  is  re- 
quired, and  hence  the  delicacy  of  the  instrument  is  as- 
sured. 


158  DETERMINATION  OF  CANE-SUGAR. 

On  filling  the  observation-tube  with  water,  and  placing 
the  zero  of  the  vernier  to  correspond  to  that  of  the  scale, 
an  observation  through  the  ocular  shows  a  vertical  line 
separating  two  half-disks,  which  should  appear  of  the 
same  intensity.  If  they  are  not,  the  instrument  is  rectified 
by  turning  in  one  direction  or  the  other  the  button  O 
shown  in  the  figure,  which  rotates  a  Mchol  prism.  When 
the  whole  surface  of  the  field  is  of  a  uniform  color,  and  the 
zero  of  the  scale  corresponds  exactly  to  that  of  the  vernier, 
the  apparatus  is  properly  adjusted,  and  is  ready  for  the 
examination  of  sugar  solutions.  The  normal  weight 
(16.19  grins. ),  the  amount  of  dilution,  etc.,  are  the  same 
as  in  the  case  of  the  Soleil-Duboscq  saccharimeter  (page 
135).  When  the  observation-tube  is  filled  with  solution  and 
placed  in  the  saccharimeter,  on  viewing  the  luminous  field 
through  the  ocular  it  will  be  seen  that  the  equality  of  tone 
in  the  two  half -disks  no  longer  exists,  one  of  the  latter  being 
much  brighter  than  the  other.  The  arm  P  is  now  slightly 
moved,  and  it  is  observed  whether  the  inequality  increases 
or  diminishes.  If  .the  inequality  increases,  it  is  necessary 
to  turn  P  in  the  opposite  direction  ;  if  it  diminishes,  it  may 
be  made  to  disappear  entirely  by  continuing  the  rotation  of 
the  arm.  When  the  field  assumes  a  uniform  tinge,  and  the 
vertical  line  has  entirely  disappeared,  the  rotation  is  ceased 
and  the  scale  read.  The  saccharimeter  is  provided  with 
two  scales  on  the  circular  plate,  one  indicating  angular 
degrees,  and  the  other  percentages  of  sugar.  A  scale  for 
milk-sugar  and  diabetic  sugar  is  added  in  some  instru- 
ments. 

In  both  of  Duboscq's  saccharimeters  a  thickness  of  one 
millimetre  of  quartz  corresponds  to  an  angular  rotation  of 
21.48°,  which  is  also  equal  to  that  produced  by  a  sugar  so- 


SHADOW  SACCHARIMETERS.  159 

lution  containing  16.19  grms.  of  pure  sugar  in  100  c.c. 
The  light  used  is  monochromatic,  and  may  be  obtained  by 
means  of  the  Laurent  lamp  (Fig.  19J-). 

Duboscq's*  saccJiarimetre  d  penombre  is  much  used  in 
France,  is  very  accurate,  not  expensive,  and,  with  the  im- 
provements recently  made  upon  it,  is  one  of  the  most  use- 
ful sacchariineters  we  have.  It  has  the  advantage,  shared 
by  all  shadow  saccharimeters,  that  persons  who  are  color- 
blind are  not  necessarily  prevented  from  working  with  it. 

SCHMIDT   AND   HANSCIl's   SHADOW   SACCHAEIMETEE. 

This  instrument  is  of  the  same  general  form  of  the  Soleil- 
Ventzke  saccharimeter,  though  it  differs  materially  in  the 
optical  portions.  It  makes  use  of  the  wedge-shaped  quartz 
compensator  and  Jellett's  prism  (Fig.  21).  Ordinary  lamp- 
light, and  not  the  monochromatic  flame,  is  required.  Stam- 
mer, f  who  has  examined  it,  recommends  the  apparatus 
highly,  not  only  for  the  sharpness  and  delicacy  of  its  read- 
ings, but  also  for  the  facility  with  which  colored  solutions 
may  be  observed.  It  is  provided  with  the  ordinary  obser- 
vation-tubes of  200  mm.  length,  and  also  of  400  mm.  and 
600  mm.  for  the  accurate  testing  of  dilute  sugar  solutions. 
The  readings  show  percentages  of  sugar,  and  not  circular 
degrees  4 

LAURENT'S  SACCHARIMETER. § 

This  apparatus  differs  materially 'from  the  preceding  in 

*  Makers'  address :  J.  &  A.  Duboscq,  21  Rue  de  1'Odeon,  an  fond  de  la  cour, 
Paris. 

f  Lehrbuch  der  ZucJcerfabr.,  Erganzungsband,  431.  Zeit.  f.  Rubenzucker, 
1880,  1098. 

\  Makers'  address  :  Stallschreiber  Strasse,  No.  4,  Berlin. 

§  Maker's  address  :  L.  Laurent,  21  Rue  de  1'Odeon,  Paris. 


160 


DETERMINATION   OF   CANE-SUGAR. 


its  optical  parts,  though,  the  phenomena  incident  to  the 
different  appearances  of  the  field  are  similar. 
Figures  22  and  23  show  the  construction :  a  (Fig.  22)  is 


Fig.  22, 


Fig.  23. 


a  thin  plate  of  bichromate  of  potassium,  which  serves  to 
cut  off  any  blue  or  violet  rays  in  the  sodium  light,  thus 
rendering  it  more  fully  monochromatic  ;  &,  the  polarizer,  is 


.\ 

LAURENT'S   SACCHARIMETER.  161 

vv/ 

X 

a  calc-spar  prism.  These  two  parts  are  placed  in  the  mov- 
able brass  tube  A  B  (Fig.  23),  which  may  be  kept  in  any 
desired  position  by  a  set  screw  at  ft.  c  is  a  round  dia- 
phragm covered  by  a  plate  of  glass,  to  which  is  cemented  a 
thin  section  of  quartz,  cut  parallel  to  its  axis,  in  such  a 
manner  that  only  one-half  of  the  aperture  is  covered  by  it ; 
e  is  the  analyzing  Nichol,  and  f  g  the  lenses  of  the  tele- 
scope. The  general  arrangement  of  the  instrument  may  be 
readily  seen  from  the  cuts. 

The  theory  of  the  saccharimeter  is  as  follows  :  If  we  sup- 
pose the  plane  of  polarization  to  be  vertical  to  the  optical 
axis  of  the  quartz  plate,  the  light  will  traverse  it  without 
deviation  ;  if  the  analyzer  is  rotated,  we  pass  progressively 
to  the  maximum  or  total  extinction  of  the  light.  Conse- 
quently, if  we  turn  the  analyzer  through  any  given  ongle, 
a,  to  the  right,  the  plane  of  polarization  being  no  longer 
parallel  to  the  axis  of  the  crystal,  the  polarized  ray  will 
pass  without  deviation  on  the  right  side,  on  which  there  is 
no  quartz  ;  but  on  the  left  it  will  be  deviated,  and  there  will 
be  determined  on  this  side  a  principal  section  symmetrical 
to  that  of  the  polarizer  on  the  right  side,  forming  an  angle 
equal  to  a,  but  to  the  left.  If  now  we  turn  the  analyzer 
until  its  principal  section  is  perpendicular  to  that  of  the 
polarizer,  there  will  be  a  total  extinction  of  the  light  to  the 
right,  but  only  partial  to  the  left.  On  the  contrary,  if  the 
principal  section  of  the  analyzer  is  perpendicular  to  that 
which  corresponds  to  the  quartz  plate,  then  there  will  be 
total  extinction  to  the  left  and  partial  to  the  right.  If, 
finally,  the  principal  section  of  the  analyzer  is  intermediate 
in  position — that  is,  perpendicular  to  the  axis  of  the  crys- 
tal or  horizontal — there  will  be  partial  extinction  both  to  the 
right  and  left,  and  of  equal  intensity,  and  the  luminous  disk 


162  DETERMINATION   OF  CANE-SUGAR. 

constituting  the  field  of  the  instrument  will  appear  uni- 
formly in  shadow.  We  can  readily  see  from  the  foregoing 
that  the  smaller  the  angle  a,  the  darker  the  shadow,  and 
also  that  a  small  rotation  of  the  analyzer  tends  to  break 
the  uniformity  of  the  shadow  ;  hence  the  saccharimeter  is 
more  sensitive  when  the  angle  a  is  less.  With  solutions 
much  colored,  by  turning  A  B,  Fig.  23,  we  augment  the 
angle,  by  that  means  greatly  brightening  the  field,  thus  en- 
abling the  operator  to  work  with  darker  solutions  than 
could  be  used  otherwise.  This  is  a  considerable  advan- 
tage, and  forms  a  distinguishing  peculiarity  of  the  Laurent 
saccharimeter. 

On  looking  through  the  ocular  of  the  apparatus,  and 
turning  the  analyzer  until  the  medial  line  disappears  and  a 
uniform  shadow  is  obtained,  if  the  zero  of  the  vernier  does 
not  exactly  correspond  to  that  of  the  scale,  it  may  be  made  to 
do  so  by  moving  the  screw  L,  Fig.  23.  The  apparatus  figured 
only  indicates  circular  -degrees,  but  it  is  now  made  with  a 
scale  reading  directly  percentages  of  sugar.  As  with  the 
Duboscq  shadow  saccharimeter,  16.19  grammes  (the  normal 
weight)  of  pure  sugar  in  100  c.c.  is  equivalent  to  an  angular 
rotation  of  21.48°,  or  100  divisions  of  the  scale,  each  corre- 
sponding to  one  per  cent,  of  cane-sugar.  The  light  used  is 
that  of  the  sodium  flame  (Fig.  19£). 

The  Laurent  saccharimeter  is  a  valuable  instrument,  and 
has  been  adopted  for  use  in  the  French  Government  labora- 
tories for  the  analysis  of  sugar.  It  has  recently  been  im- 
proved so  as  to  differ  somewhat  from  the  form  above  de- 
scribed, mainly  in  the  direction  of  mechanical  alterations, 
so  as  to  work  with  a  longer  observation-tube  ;  and  in  some 
other  respects. 


COMPARISON  OF  SACCHARIMETERS.  163 


EQUIVALENCE  IN  DEGREES  OF  DIFFERENT  SACCHARIMETERS. 


1°  Scale  of  Mitscherlich         =  .750    grin,  sugar  in  100  c.c. 
1°     "          Soleil-Duboscq      =  .1619     "        "  " 

1°     "          Yentzke-Soleil      =  .26048  "        "  " 

1°     "          Wild  (sugar  scale)  =  .1000     "        "  " 

1°     u          Shadow  saccliar. 

(of  Laurent  and  Duboscq)  =  .1619     "        "  " 

1°  Mitscherlich  =  4.635°  Soleil-Duboscq. 

1°  "  =  2.879°  Soleil-Yentzke. 

1°  Soleil-Duboscq       =     .215°  Mitscherlich. 
1°       "  "  =     .620°  Yentzke-Soleil. 

1°       "  "  =  1.619°  Wild. 

1°      "    Yentzke         =     .346°  Mitscherlich. 
1°       "  =  1.608°  Soleil-Duboscq. 

1°       "  "  =  2.648°  Wild. 

1°  Wild  (sugar  scale)  =     .618°  Soleil-Duboscq. 
1°       u  "  =     .384°  Soleil-Yentzke. 

1°       "  "  =     .133°  Mitscherlich. 

Equivalence  in  Circular  Degrees. — 

Wild  (sugar  scale)  1°  =  .1328  circular  degree  D 
Soleil-Duboscq    j  1°  =  .2167        "          "       D 
u  j  1°  =  .2450        "          "        j 

Soleil-Yentzke     j  1°  =  .3455        "          "       D 
j  1°  =  .3906        "          "        j 

Instruments  reading  angular  degrees,  such  as  Wild's, 
Laurent's,  and  Duboscq' s  saccharimetre  a  penombre,  may 
be  made  to  give  the  concentration — i.e.,  the  number  of 
grammes  of  sugar  in  100  c.c.  of  solution— by  the  following 
formula : 

100  a 
~  Tc  [a]D 


164  DETERMINATION  OF  CANE-SUGAR. 

in  which  the  observed  angle  of  rotation  is  a,  Tc  the  length 
of  the  observation- tube  in  decimetres,  and  [a]  D  the  speci- 
fic rotatory  power  of  cane-sugar,  which  for  most  purposes 
may  be  placed  at  66.4°.  When  the  specific  gravity  of  the 
solution  operated  upon  is  known,  the  percentage  by  weight 
can  be  calculated  by  dividing  the  value  of  c  obtained  as 
above,  by  the  density. 

DECOLORIZING   OF  THE  SUGAR  SOLUTION. 

Basic  Lead  Acetate. — The  sugar  solution  to  be  tested 
in  the  optical  saccharimeter  is  commonly  more  or  less  dark 
and  requires  to  be  decolorized.  For  this  purpose  the  most 
ordinarily  used  and  effective  reagent  is  the  solution  of  the 
basic  lead  acetate.  It  is  prepared  by  boiling  for  half  an 
hour,  four  hundred  and  forty  grammes  of  neutral  lead  ace- 
tate with  two  hundred  and  sixty-four  grammes  lead  oxide 
(litharge),  and  one  and  a  half  litres  of  water,  and  diluting 
when  cool,  to  two  litres  ;  after  standing  some  time  the  clear 
liquid  may  be  siphoned  off  from  the  insoluble  residue. 
The  solution  has  a  density  of  1.267. 

Alum. — Kohlrausch  recommends  the  employment  of 
alum  solution  in  connection  with  the  lead  salt,  which,  by 
forming  sulphate  of  lead,  tends  to  more  completely  preci- 
pitate the  coloring  matter  than  when  the  acetate  is  used 
alone  ;  sulphate  of  soda  and  other  salts  have  also  been  sug- 
gested, though  the  chemical  action  is  similar  to  that  of 
alum.  Woussen  *  adds  a  little  tannin  solution,  before  the 
addition  of  the  lead  salt,  for  very  colored  solutions. 

Hydrate  of  Alumina. — Dr.  Scheibler  f  prefers  the  use 
of  precipitated  hydrate  of  alumina  dispersed  in  water  as 

*  De  V Analyse  des  Sucres,  34. 

f  Zeits.  f.  Rubenzuckerind.  des  Deut.  Reiches,  1870,  223. 


ERROR  FROM  LEAD.  165 

a  decolorizing  agent,  especially  in  highly -colored  solutions. 
For  the  products  of  the  beet  this  agent  works  well,  but  for 
low  cane-sugars  and  molasses  the  decolorizing  power  is 
entirely  insufficient  when  used  alone.  This  reagent  is  pre- 
pared by  precipitating  a  solution  of  alum  with  caustic  am- 
monia in  slight  excess,  and  washing  the  resulting  magma 
until  the  washings  cease  to  render  red  litmus-paper  blue. 
After  the  addition  of  the  alumina  to  the  sugar  solution 
it  should  stand,  with  frequent  shaking,  for  five  or  ten 
minutes  before  filtering. 

Error  from  Use  of  Lead  Solution. — There  is  one  ob- 
jection to  the  excessive  use  of  lead  which  has  not  received 
the  attention  from  sugar  chemists  that  its  importance 
merits — viz.,  the  influence  which  the  basic  acetate  of  lead 
exerts  upon  in  vert -sugar  in  increasing  its  rotatory  power. 
C.  H.  Gill  *  first  pointed  out  this  source  of  error  in  sac- 
charimetric  determinations,  and  explained  the  action  by 
asserting  that  a  compound  of  basic  lead  salt  and  levulose 
was  formed.  My  own  experiments  f  amply  confirm  his  re- 
sults. The  tendency  of  the  error  is  to  increase  with  the 
amount  of  invert-sugar  with  the  quantity  of  lead  solution 
added ;  hence  the  error  will  be  greatest  in  the  darker- 
colored  solutions,  which  generally  not  only  contain  a  large 
portion  of  invert-sugar,  but  also  require  a  proportionate 
amount  of  the  clarifying  liquid.  For  solutions  poor  in 
invert-sugar,  and  for  which  little  lead  solution  is  required, 
the  error  becomes  very  small  and  may  be  altogether  neg- 
lected for  all  ordinary  work.  For  solutions  requiring  more 
lead  the  least  quantity  should  be  added  that  will  give  a 

*Journ.  CTiem.  Boe.,  April,  1871. 

f  I.   White  refined  sugar  free  from  invert-sugar  polarized  90.3.     After  the 


166  DETERMINATION  OF  CANE-SUGAR. 

solution  capable  of  being  reliably  tested  in  the  sacchari- 
meter. 
Error  from  the  Volume  of  Lead  Precipitate. — The 

voluminous  precipitate  produced  by  lead  in  raw  sugar  so- 
lutions is  itself  a  source  of  error.  Scheibler*  states  that 
100  c.c.  beet-juice  with  10  c.c.  lead  solution  gave  a  pre- 
cipitate whose  volume  was  1.3  c.c.,  which,  by  taking  the 
place  of  the  water  in  the  flask,  was  equivalent  to  filling  the 
latter  to  98.7  c.c.  instead  of  100  c.c.,  introducing  an  error  of 
.15  per  cent.  Nebel  and  Sostmanf  found  for  beet- juice  the 
error  to  be  .17  per  cent.,  and  with  diffusion  juices  .27  per 
cent.  Pellet  £  gives  the  following  as  the  greatest  error  from 
this  source:  for  beet-juice,  .15  per  cent,  to  .20  per  cent.; 
cane- juice,  .10  per  cent. ;  masse  cuite,  .25  per  cent. ;  second 

addition  of  9  per  cent,  by  volume  of  solution  of  basic  lead  acetate  it 

polarized  90.2. 
II.   Centrifugal  raw  sugar  containing  2.74  per  cent,  invert-sugar,  polarized 

85. 7  without  lead. 

With  2  per  cent,  lead  solution  it  polarized  85.6. 
"With  5        "  "  "  85.7. 

With  9        "  "  «  85.8. 

III.  Muscovado  sugar  containing  5  per  cent,  invert-sugar,  polarized  without 

lead  75.0. 

"With  6  per  cent,  lead  solution,  75.8. 
With  9        "  "  75.9. 

IV.  Low-grade  refined  sugar  containing  8  per  cent,  invert-sugar,  polarized 

77.0. 

With  2  per  cent,  lead  solution,  77.3. 
With  5        "  "  77.5. 

With  9        "  "  78.2. 

V.  Sugar-house  syrup  containing  28  per  cent,  invert-sugar,  polarized  13.1. 
With  4  per  cent,  lead  solution,  13.3. 
With  8        "  "  13.7. 

Another  solution  polarized  12.8. 

With  10  per  cent,  lead  solution,  13.7. 
The  lead  solution  itself  has  no  action  on  the  polarized  ray. 

*  Zeits.  f.  Zuclcerind.  des  Deut.  Reiches,  1875,  1054. 
\Ilid.,  1876,  724.  \  Ibid.,  1876,  730. 


ERROR  FROM  LEAD-PRECIPITATE.  167 

and  third  product  sugars  (beet),  .25  per  cent.;   molasses 
(beet),  .63  per  cent. 

Scheibler  *  gives  the  following  way  of  eliminating  this 
error,  which  he  calls  the  method  of  double-dilution:  To 
100  c.c.  of  the  sugar  solution  10  c.c.  of  lead  solution  are 
added  and  the  saccharimetric  reading  taken.  A  second 
solution  is  prepared  by  mixing  the  same  volumes  of  the 
saccharine  liquid  and  lead  solution,  which  is  diluted  to  220 
c.c.  and  polarized.  The  last  reading  is  doubled  and  sub- 
tracted from  the  first,  the  difference  multiplied  by  2.2,  and 
this  product  taken  from  the  first  reading.  This  last  result 
constitutes  the  corrected  sugar  content.  Example  : 

A  sugar  solution  gave  a  saccharimetric  reading  of  47.10. 
After  dilution 23.40. 

(1)  23.40  X  2  =  46.80 ;  47.10  -  46.80  =  .30. 

(2)  ..30  X  2.2  =  .66  ;  47.10  -  .66  =  46.44. 

It  often  happens  that,  even  after  the  addition  of  an  ex- 
cessive quantity  of  lead  solution,  the  filtered  liquid  retains 
a  strong  brown  color,  rendering  it  unfitted  to  give  an  accu- 
rate reading.  In  this  case  a  shorter  observation-tube  may 
be  used  or  the  solution  made  of  half  the  normal  strength. 
This  mode  of  proceeding  is,  however,  open  to  the  objection 
that  the  necessary  doubling  of  the  reading  increases  the 
errors-  of  observation. 

Bone-Black. — This  is  the  agent  best  suited  to  assist 
lead  in  the  decolorization  of  raw  sugar  solutions.  For  this 
purpose  a  quantity  of  well-dried,  powdered  black  should 
be  kept  on  hand  in  a  tight  bottle  with  a  wide  mouth,  fitted 
with  a  stopper  that  carries  a  glass  tube  the  end  of  which  is 

*  Zeits.  /.  Zuckerind.,  1875,  1054. 


168 


DETERMINATION  OF  CANE-SUGAR, 


Fig.  24, 


kept  closed  with  a  small  cork  when  the  bottle  is  not  in 
use  (Fig.  24).  The  bone-black  should  be  dried  at  120°  for 
two  hours. 

After  the  addition  of  lead  the  flask  is 
filled  up  to  the  mark  with  water,  shaken, 
about  one-half  of  the  contents  poured  out, 
the  black  dusted  into  the  liquid  remaining  in 
the  flask,  which  is  agitated  vigorously  a  few 
moments  and  filtered.  The  least  quantity  of 
black  should  be  used  that  will  be  sufficient  to 
decolorize  the  solution. 

Art  animal  black  of  very  superior  decolor- 
izing power  may  be  prepared  from  bone- 
black  in  grains,  such  as  is  used  in  the  sugar 
manufacture.  To  the  char  to  be  treated,  about 
one-third  to  one-half  more  hydrochloric  or 
nitric  acid  is  added  than  is  necessary  to  dis- 
solve all  the  phosphate  and  carbonate  of  lime  present,  and 
the  mixture  is  warmed  several  hours  to  promote  solution  (the 
more  thorough  the  solution  of  the  mineral  matter  the  higher 
the  decolorizing  power  of  the  carbon  Will  be).  It  is  then  tho- 
roughly washed  with  boiling  water  until  the  washings  cease 
to  redden  litmus-paper.  After  the  washing  is  complete  the 
carbon  is  dried  at  120°  and  finely  powdered  for  use,  though 
the  grains  may  be  used  for  filtering  in  tubes.  Bone-black 
well  prepared  according  to  this  method  has  a  much  greater 
decolorizing  effect  than  the  ordinary,  and  hence  a  small 
quantity  may  be  taken  for  a  test.  The  most  obstinate  so- 
lution may  be  readily  decolorized  by  its  aid  with  a  mode- 
rate quantity  of  lead  solution. 

Absorption  of  Sugar  I>y  Bone-Black. — Animal  char- 
coal has  the  property  of  absorbing  sugar  from  its  solutions. 


ERROR  FROM  BONE-BLACK.  169 

Scheibler  *  has  found  that  5.5  grins,  dried  black  shaken 
with  50  c.c.  of  a  solution  containing  13.024  grms.  of  cane- 
sugar,  renders  the  polarization  .4  percent,  to  .5  per  cent,  too 
low.  J.  M.  Merrick  f  has,  by  a  series  of  experiments,  fully 
proven  the  existence  of  this  source  of  error  in  the  saccha- 
rimetric  determination.  His  results  agree  with  those  of 
Scheibler.  When  the  sugar  solution  is  filtered  through  a 
column  of  black,  the  first  third  should  be  rejected  and  the 
test  made  on  the  remainder  of  the  filtrate,  which  may  be 
confidently  relied  upon  to  contain  the  normal  amount  of 
sugar.  The  error  arising  from  the  absorption  of  sugar  by 
the  bone-black  may  be  corrected  by  determining  the  ab- 
sorption coefficient  of  the  dried  black.  It  is  good  practice 
to  use  both  bone-black  and  lead  on  all  low-grade  solutions, 
but  in  moderate  quantity,  as  the  errors  tend  to  counter- 
balance each  other.  For  50  c.c.  of  the  Yentzke  sugar  nor- 
mal solution  with  the  specially  prepared  black,  there  may 
be  used  from  J  per  cent,  to  3  -per  cent,  by  volume  of  lead 
solution,  and  from  J  grm.  to  1  grm.  of  char  for  all  products 
of  moderate  difficulty.  For  molasses  and  the  most  trou- 
blesome cases  it  will  be  found  that  very  rarely  will  more 
than  5  per  cent,  of  lead  solution  and  1  to  2  grms.  of  char 
be  necessary.  When  the  bone-black  is  used  in  the  quanti- 
ties indicated  above  no  correction  need  be  made  for  its  ab- 
sorbing power  for  sugar.  Even  when  working  with  ordinary 
bone-black  two  grammes  are  generally  sufficient  for  all  but 
the  worst  cases  . 


*  Zeits.  f.  ZucJcerind.  des  Deut.  Reiches,  1870,  218. 

f  Chem.  News,  xxxviii.  33. 

$  II.  A.  Mott  (Journ.  Am.  Chem.  Soc.,  i.  12),  working  with  the  Vcntzke  nor- 
mal solution,  has  found  that  ten  grammes  of  char  absorb  the  following  quan- 
tities of  sugar  : 


170  DETERMINATION  OF  CANE-SUGAR. 

PREPARATION   OF   PURE   SUGAR. 

The  purest  loaf-sugar  of  commerce  is  reduced  to  a  fine 
powder,  placed  in  a  funnel  whose  barrel  is  stopped  with  a 
plug  of  raw  cotton  or  sponge,  and  85  per  cent,  alcohol 
poured  upon  it.  This  is  allowed  to  percolate  through  the 
mass  until  a  volume  of  alcohol  has  passed  through  equiva- 
lent in  bulk  to  about  three  times  that  of  the  sugar.  The 
latter  is  then  drained,  air-dried,  powdered  again,  and  final- 
ly dried  in  small  quantities,  at  a  time  when  it  is  needed,  at 
a  water-bath  heat  for  half  an  hour.  Sugar  thus  prepared 
may  be  confidently  relied  upon  to  indicate  one  hundred 
per  cent,  of  cane-sugar  with  a  correct  saccharimeter. 

ERRORS  INHERENT  IN   THE    OPTICAL    METHOD    OF  ESTIMAT- 
ING  CANE-SUGAR. 

1.  Influence  of  Temperature. — Though  the  specific 
rotatory  power  of  cane-sugar  is  not  dependent  in  any  marked 
degree  on  the  temperature  at  which  the  observation  is 
taken,  yet  the  temperature  has  some  eifect,  owing  to  a  va- 
riety of  causes,  among  which  are  (1)  the  alteration  in  the 
length  of  the  observation-tube  by  changes  of  heat,  (2)  the 
increase  in  volume  of  the  sugar  solution  in  the  tube  and 
consequent  change  in  density,  and  (3)  the  expansions  and 
contractions  produced  in  the  quartz  plates  and  other  parts 
of  the  apparatus.  Mategczek  *  gives  a  table  of  the  cor- 
rections to  be  made  at  various  temperatures  for  the  Soleil- 
Yentzke  and  the  Soleil-Duboscq  instruments,  17^°  C.  being 
taken  as  a  standard  : 

With  pure  sugar,  .30  per  cent,  to  .35  per  cent. 

"    raw  sugars,  .10        "  .66        " 

Also,  that  some  bone-blacks  absorb  in  a  different  ratio  from  others. 
*  Zeits.  f.  ZucJcerind.  des  Dent.  Reiches,  1875,  877,  891. 


ERROR  FROM  TEMPERATURE. 


171 


Temp. 

Soleil-Ventzke. 

Soleil-Duboscq. 

Reading  at  given 
temp. 

II. 

Reading  at  given 
temp. 

II. 

IO° 

IOO.I7 

26.004 

II 

100.  14 

26.010 

12 

IOO.  12 

26.016 

1-7 

IOO.IO 

26.022 

IOO.O8 

26.028 

15 

100.05 

26.034 

100.05 

16.181 

16 

100.03 

26.039 

IOO.O3 

16.184 

17 

100.01 

26.045 

IOO.OI 

16.188 

I7i 

IOO.OO 

26.048 

100.00 

16.190 

18 

99-99 

26.051 

99.99 

16.192 

19 

99.96 

26.057 

99.96 

16.196 

20 

99.94 

26.064 

99-94 

16.200 

21 

99.91 

26.071 

99.92 

16.203 

22 

99.88 

26.078 

99.89 

16.207 

23 

99-35 

26.086 

99.87 

16.211 

24 

99.83 

26.093 

99-85 

16.215 

25 

99.80 

26.100 

99.82 

16.218 

26 

00.77 

26.108 

27 

00.74 

26.116    , 

28 

QQ.7I 

26.124 

2Q 

QQ.68 

26.132 

30 

99-65 

26.139 

The  numbers  in  the  second  column  indicate  the  quanti- 
ties to  be  weighed  at  corresponding  temperatures  to  give  a 
correct  reading  at  17J-0  C.  If  the  correction  is  taken  from 
the  first  column,  the  ordinary  normal  quantity  must  be 
weighed. 

For  saccharimeters  reading  circular  degrees,  the  correc- 
tion is  made  by  adding  the  product  of  the  difference  in 
temperature  from  the  normal  17°  C.  and  the  factor  .011,  to 
the  degree  read,  when  the  temperature  is  above  17°,  or  sub- 
tracting when  it  is  below.  As,  for  example,  the  reading  is 
25°  at  20°  C.  ;  then  20  — 17  ^  3  X  .011  =  .033,  which,  add- 
ed to  25°,  makes  25.033°  as  the  corrected  result.  This  is 
for  solutions  of  25  grms.  to  100  c.c.,  approximately. 

II.  Personal  Error. — In  all  saccharimeters  where  the 


172  DETERMINATION  OF  CANE-SUGAR. 

reading  is  taken  by  a  comparison  of  the  equality  of  tint  of 
two  half -disks,  there  is  a  small  but  pretty  constant  source 
of  inaccuracy  in  the  results,  owing  to  the  fact  that  all  eyes 
are  not  equally  sensitive  to  minute  differences  of  color. 
The  same  observer  at  different  times  of  the  day  and  in  dif- 
ferent conditions  of  the  eye,  from  its  being  more  or  less 
fatigued,  will  give  varied  readings.  Some  persons  are  spe- 
cifically unfitted  for  work  with  the  polariscope  having  a 
field  of  two  colors,  on  account  of  color-blindness ;  but  this 
is  not  true  of  the  shadow  saccharimeters  or  that  of  Wild. 
Dr.  Landolt  *  has  made  a  careful  determination  of  this 
error  with  the  aid  of  five  experienced  polarizers,  and  finds 
it  to  be,  with  the  Soleil-Ventzke,  the  Soleil-Duboscq,  and 
the  Wild  saccharimeters,  from  .3°  per  cent,  to  .5°  percent., 
plus  or  minus.  Probably  this  will  be  considered  too  high  ; 
±.2°  per  cent,  would  better  represent  the  average.  The  per- 
sonal error  doe's  not  necessarily  affect  the  ultimate  accuracy 
of  the  results,  for  each  operator  can  set  the  scale  of  the  in- 
strument to  suit  his  own  eye  ;  and  if  more  than  one  use  the 
same  instrument,  each  can  have  his  personal  correction. 
Thus,  if  one  operator  reads  the  zero-point  at  —  .4°  and 
another  at  zero,  the  former  will  have  to  add  .4°  to  all  of  his 
readings,  f 


*  American  Chemist,  iv.  18-20. 

f  Tollens  (Ber.  Deut.  Chem.  Ges.,  1877,  1403)  and  Schmitz  (ibid.,  1877, 
1414)  have  proved  that  the  sp.  rotatory  power  of  cane-sugar  is  not  constant  for 
solutions  of  all  concentrations.  The  effect  on  the  results  of  the  optical  estima- 
tion of  cane-sugar  is  too  small  to  be  taken  into  account  for  technical  work, 
being  less  than  one-tenth  of  one  per  cent,  in  all  instruments.  Elaborate  tables 
of  the  correction  for  the  different  instruments  have  been  calculated,  and  may 
be  found  in  the  places  cited,  and  also  in  Stammer's  Lehrbuch  der  Zuckerfahri- 
kation  and  Landolt's  Optische  Drehungsvermogen. 


OPTICALLY  INACTIVE  SUGAR.  173 

ERROR  OWING    TO    PRESENCE    OF    INVERT-SUGAR — OPTICAL 
INACTIVITY   OF    INVERT-SUGAR. 

All  raw  sugars  and  molasses  from  the  cane  contain  in- 
vert-sugar, sometimes  in  large  amounts.  Inasmuch  as  the 
rotatory  power  of  invert-sugar  made  by  acting  upon  cane- 
sugar  with  acids,  is  strongly  to  the  left,  a  mixture  of  the 
two  will  give  in  the  saccharimeter  a  reading  too  low  as  ex- 
pressing the  cane-sugar.  It  has  been  considered  that  the 
invert-sugar  in  the  products  of  the  cane  possesses  the  same 
rotatory  power  as  that  artificially  prepared,  and  it  was  cus- 
tomary with  some  chemists  to  correct  their  polariscopic 
readings  by  adding  to  them  -fife  of  the  invert-sugar  as 
found  by  the  estimation  with  copper  liquor. 

Recent  researches  of  Girard  and  Laborde  *  tend  to  verify 
a  previous  observation  of  Dubrunfaut — that  the  invert- 
sugar  in  cane  products  is  optically  inactive,  and  hence  the 
use  of  the  coefficient  -ffe  involves  an  error.  The  results  of 
the  above  chemists  are  based  on  the  examination  of  (1)  syr- 
ups artificially  prepared  from  raw  cane-sugars  of  many 
sources  ;  (2)  of  molasses  from  the  sugar  plantations  ;  and 
(3)  from  the  refiner's  molasses.  The  cane-sugar  was  esti- 
mated directly  with  the  polariscope,  and  also  very  careful- 
ly by  inversion  and  gravimetric  determination  with  copper 
liquor.  The  invert-sugar  was  determined  in  the  same  man- 
ner. In  the  majority  of  the  samples  examined  the  per- 
centage of  sugar  by  the  copper  method  agreed  quite  close- 
ly with  that  by  direct  polarization,  the  latter  being  as 
often  above  as  below  the  former. 

Other  investigators,  among  whom  may  be  mentioned 
Muntz  (J.  des  Fabricants*  xvii.  No.  5),  Morin  (Sucrerie 


*  Journ.  des  Fabricants,  xvii.  No.  5. 


174  DETERMINATION  OF  CANE-SUGAR. 

Indigene,  xii.  158),  Grill  (Sugar-Cane,  July,  1878),  and  Halse, 
have  confirmed  the  conclusions  of  the  French  chemists  by  an 
extended  series  of  experiments  upon  raw  sugars  of  all  ori- 
gins, cane-juice,  molasses,  etc.  Morin  shows  that  analyses 
of  raw  sugar  corrected  by  the  coefficient  -ffa  generally  add 
up  over  100,  even  when  large  amounts  of  undetermined 
organic  matters  are  present.  As  beet  sugars  and  syrups 
rarely  contain  more  than  traces  of  invert-sugar,  these  re- 
sults have  no  special  application  in  that  direction. 

Meissl  *  has  recently,  by  a  most  elaborate  investigation, 
gone  over  the  ground  covered  by  the  authorities  named, 
with  the  result  of  completely  contradicting  both  their  facts 
and  conclusions.  Working  with  seven  low-grade  raw 
sugars  from  the  cane,  carrying  from  5  to  13  per  cent,  in- 
vert-sugar, and  determining  the  cane-sugar  after  inversion, 
and  the  invert-sugar  directly,  by  Soxhlet's  improved  mani- 
pulation with  Fehling'  s  solution  (page  201),  he  finds  the  cane- 
sugar  by  inversion  to  be  always  considerably  higher  than 
the  saccharimetric  reading,  the  difference  varying  with  the 
amount  of  invert-sugar  present ;  that  by  the  use  of  the 
coefficient  £fa  the  corrected  percentage  of  sugar  agrees 
closely  with  that  by  inversion  ;  that  the  syrups  extracted 
froni  these  sugars  by  alcohol,  and  containing  from  27  to  39 
per  cent,  invert-sugar,  give  essentially  the  same  results  as 
above.  He  also  proves  that  the  sugars,  on  complete  analy- 
sis, do  not  add  up  over  100,  but  the  quantity  of  organic 
matters  not  sugar,  varies  from  1  to  8  -per  cent.  Meissl  consi- 
ders the  conclusion  of  the  chemists  cited,  as  to  the  optical 
inactivity  of  invert-sugar  in  commercial  products,  as  erro- 
neous, and  ascribes  the  error  to  the  use  of  the  gravimetric 

*  Zeits.  f.  Rubenz.,  xxix.  1034;  Stammers  Jahresb.  (abstract),  xix.  178. 


POLARIZING  EFFECT  OF  VARIOUS  BODIES. 


175 


method  with  Fehling's  solution,  which,  he  claims,  gives  re- 
sults that  are  too  high  (page  203). 

The  coefficient  -ffc  is  inadmissible,  however,  for  general 
commercial  work,  because  sugars  are  bought  and  sold  (at 
least  in  the  United  States)  on  the  direct  polarization,  and  it 
would  be  clearly  wrong  to  make  the  correction  unless  the 
matter  was  so  understood  by  the  merchant. 

See  also  Horsin-Deon.* 


INFLUENCE    OF    VARIOUS     BODIES     ON    THE     POLARISCOPIC 

READINGS. 

Alcohol. — The  presence  of  alcohol  in  solutions  of  cane- 
sugar  does  not  alter  materially  the  specific  rotatory  power  ; 
it  diminishes  the  rotatory  power  of  invert-sugar  (Jodin— 
see  Invert-Sugar,  page  89). 

Alkalies. — Caustic  soda,  ammonia,  and  potash  lower 
the  saccharimetric  titre,  according  to  Sostman,t  and  the 
effect  may  be  represented  quantitatively  as  follows  : 


Alkali  in  100  c.c. 

Strength  of  solution  in  sugar. 

5  grms.  in  ico  c.c. 

10  grms.  in  100  c.c. 

20  grms.  in  100  c.c. 

I  grm.  K2O 
i     "    Na20 

.426  per  cent. 
•450       " 

.65    per  cent. 
.907 

.915  per  cent. 
1.217        " 

*  Jr.  Fabr.  Sucre,  xx.  No.  37. 

fSostman,  Zeits.  f.  Zuckerind.  des  Deut.  Reiches,  1866,  272. 


176  DETERMINATION  OF  CANE-SUGAR. 

Pellet's  *  results  are  somewhat  different : 


5.4  grms.  sugar 

17.3  grms.  sugar 

in  100  c.c. 

in  100  c.c. 

i  grm.  KQH 

•17 

.500 

i     "     NaOH 

.14 

•450 

i     "     NH4O 

•073 

.085 

Caustic  lime  lias  an  important  influence  in  lowering  the 
specific  rotatory  power  of  cane-sugar.  Muntz  f  gives  the 
following  in  this  relation  : 

Sugar  solution,  10  grammes  in  100  c.c.  : 

.409  gramme  sugar  to  i  molecule  CaO,  [a]  D  64.9° 

.818          "  "         i         "  "          "     61.3° 

1.637          "  "         1         "          "          "     56.9° 

3.274          "  "         2         "          "          "     51.8° 

Pure  cane-sugar  being 67.0° 

In  the  estimation  of  cane-sugar,  according  to  various  ob- 
servers, one  part  of  lime  lowers  the  rotation  equivalent 
to— 

.64  part  of  sugar  (Jodin). 
.79       "  "      (Dubrunfaut). 

1.12      "  "      (Bodenbender). 

1.22.     "  "     (Stammer). 

Baryta  and  strontia,  have  a  similar  action  to 'that  of 
lime.  On  neutralization  of  the  alkali  or  alkaline  earth 
with  acetic  or  phosphoric  acids  the  normal  rotation  is  re- 
stored. 

Mineral  Salts. — Muntz  $  has  found  that    some   salts 


*  Pellet,  Zeits.  f.  Zuckerind.  des  Deut.  Reiches,  1877, 1086. 

f  Muntz,  ibid.,  1876,  736.  £  Muntz,  ibid.,  1876,  735. 


EFFECT  OF  SALT  ON  POLARIZATION. 


177 


lower  the  specific  rotatory  power  of  cane-sugar.  Taking 
the  rotatory  power  of  sugar  at  [a]  D  =  67.0°,  he  finds,  in 
the  case  of  chloride  of  sodium : 


NaCl  added. 

Concentration  of  sugar  solution  in  100  c.c. 

5  grms. 

10  grms. 

20  grms. 

5  grms. 

10        " 

20       " 

[>]D66.i 
65.3 
63.8 

66.2 
65.3 
63.7 

66.3 
65.6 
61.0 

Carbonates  of  soda,  ammonia,  and  potash,  and  phos- 
pliate  of  soda  have  a  small  effect,  1  gramme  of  the  salts  in 
the  sugar  normal  solution  altering  the  rotation  generally 
much  less  than  .20  per  cent.  According  to  Bardy  and 
Biche,*  sulphate,  nitrate,  chloride,  and  carbonate  of  potas- 
sium, and  chloride  of  sodium  have  little  or  no  effect  on  the 
polarization.  Muntz  states  that  sulphates  of  potassium, 
sodium,  ammonium,  and  magnesium,  the  nitrates  and 
acetates  of  the  same  bases,  phosphate  of  soda,  chlorates, 
sulphides,  hypo  sulphides,  and  chlorides  of calcium,  mag- 
nesium, and  barium,  alter  the  reading  from  2  to  3  per  cent, 
when  they  are  present  dissolved  in  the  proportion  of  20 
to  30  parts  to  100  parts  of  sugar. 

CORRECTION   OF  THE  MEASURING    APPARATUS. 

The  graduated  apparatus,  as  bought  from  the  dealers,  is 
seldom  accurate,  and  requires  to  be  corrected.  For  this 
purpose  it  is  best  to  make  standard  flasks  of  100  c.c.  and 
50  c.c.  capacity,  from  which  pipettes  and  all  other  measur- 
ing apparatus  may  be  adjusted  ;  the  standards  should  be 


Sucrerie  Indigene,  x.  551. 


178  DETERMINATION  OF  CANE-SUGAR. 

kept  in  a  safe  place  and  only  used  for  purposes  of  compa- 
rison. Flasks  should  be  selected  that  will  hold  the  re- 
quired quantity  of  liquid  up  to  a  point  a  little  below  the  mid- 
dle of  the  neck  which  should  not  be  too  short.  Clean  and 
thoroughly  dry  the  flask,  place  it  on  the  pan  of  a  balance 
in  a  room  whose  temperature  is  about  16°  C.,  and  counter- 
poise with  weights ;  now,  in  the  case  of  the  100  c.c.  flask, 
weigh  99.89  grammes  of  distilled  water,  or,  for  the  50  c.c. 
flask,  49.945  grammes  at  16°  C.,  carefully  wiping  away  any 
drops  that  may  adhere  to  the  neck.  When  the  weighing 
is  completed,  mark  on  the  neck  of  the  flask  a  straight  line 
tangent  to  the  lowest  curve  of  the  meniscus  formed  by 
the  surface  of  water.  The  weight  of  water  taken  is  ex- 
actly equal  to  100  grammes,  or  50  grammes  distilled  water 
at  4°  C.,  the  temperature  of  water's  greatest  density.  If 
the  flasks  are  to  be  marked  for  two  graduations,  as  100 
c.c.  and  110  c.c.  in  one  case,  and  50  to  55  c.c.  in  the  other, 
ten  and  five  grammes  of  water  respectively  must  be  weighed 
after  the  100  and  50  marks  are  fixed,  and  another  mark 
made  on  the  neck  as  before. 

From  the  standard  flasks  standard  pipettes,  capable  of  ex- 
actly delivering  100  c.c.  and  50  c.c.,  may  be  readily  made  by 
careful  measurement  with  water,  the  mark  placed  on  the 
pipettes  indicating  the  exact  volumes  they  will  deliver  into 
the  standard  flasks.  By  means  of  the  pipettes  the  flasks 
for  general  use  in  the  laboratory  may  be  corrected  ;  for  this 
latter  graduation  no  especial  temperature  of  the  water  used 
is  required,  so  long  as  it  does  not  materially  change  during 
the  progress  of  the  correction.  In  this  manner  it  is  always 
easy,  in  a  few  moments,  to  graduate  a  flask  with  perfect  ac- 
curacy— and  in  case  of  doubt  the  standard  is  always  at 
hand. 


CHAPTER  VII. 

Determination  of  Cane-Sugar  —  Chemical  Methods. 


of  these  methods  have  only  an  historical  interest, 
and  such  will  be  but  outlined  in  description  ;  those,  how- 
ever, that  are  in  actual  use  will  be  described  in  as  much 
detail  as  the  necessities  of  each  case  demand  and  the  space 
will  permit. 

METHOD   OF  PELIGOT. 

This  process  is  based  on  the  fact  that  lime  enters  into 
combination  with  cane-sugar  in  definite  proportion,  form- 
ing a  sucrate,  so  that  when  excess  of  caustic  lime  is  added 
to  a  sugar  solution,  an  acidimetric  estimation  of  the  com- 
bined lime  gives  indirectly  the  amount  of  sugar  dissolved. 
The  method  is  only  suited  for  saccharine  products  contain- 
ing no  grape-sugar,  and  it  cannot  be  recommended  for  ac- 
curacy. It  is  executed  as  follows  :  Dissolve  ten  grammes 
of  the  sugar  to  be  tested  in  75  c.c.  of  water,  add  ten 
grammes  of  finely  -powdered  caustic  lime  to  the  solution, 
and  agitate  from  seven  to  ten  minutes,  or  until  the  lime  is 
all  combined  with  the  sugar  ;  for  weak  saccharine  liquids 
a  less  quantity  of  lime  may  be  used.  Throw  the  milky 
liquid  on  a  filter,  and  take  10  c.c.  of  the  clear  filtrate,  dilute 
toSOOc.c.,  add  a  few  drops  of  litmus  solution,  and  titre 
with  standard  acid  until  the  red  color  of  the  litmus  just  ap- 
pears. The  standard  acid  solution  is  made  by  dissolving 
twenty-one  grammes  of  monohydrated  sulphuric  acid  to  a 
litre  with  water,  that  amount  of  solution  being  capable  of 

179 


180  DETERMINATION  OP  CANE-SUGAR. 

saturating  the  lime  which  combines  with  fifty  grammes  of 
sugar;  hence,  1  c.c.  of  the  acid  solution  is  equivalent  to 
.05  gramme  cane-sugar. 

METHOD   OF  EXTRACTION  BY  ALCOHOL. 

This  is  a  method  more  particularly  suited  to  the  estima- 
tion of  the  sugar  in  plants,  and  where  the  quantities  to  be 
assayed  are  very  small ;  when  the  conditions  are  favorable 
it  is  capable  of  giving  accurate  results.  It  consists  in 
simply  extracting  the  material  with  cold  alcohol  of  specific 
gravity  .830,  and  evaporating  the  alcoholic  liquid  obtained 
to  dry  ness.  Aqueous  alcohol  will  dissolve  small  portions 
of  invert-sugar,  mineral  salts,  fat,  and  coloring  matter,  but 
these  can  be  washed  from  the  dried  residue  by  means  of 
absolute  alcohol,  which  does  not  dissolve  the  cane-sugar. 
The  process  may  be  conducted  as  follows  :  *  100  to  120 
grammes  of  the  dried  and  finely-powdered  substance  are 
treated  in  a  small  flask  with  alcohol  of  .830  specific  gravity, 
and  a  drop  or  two  of  a  very  dilute  solution  of  caustic  alkali 
is  added  to  neutralize  any  acidity,  the  alcohol  being  allowed 
to  stand  in  contact  with  the  material  under  examination, 
with  frequent  shaking,  for  three  hours  ;  filter,  add  a  fresh 
portion  of  alcohol,  allow  to  stand  two  hours  with  agita- 
tion, and  filter  again.  Repeat  this  operation  several  times, 
if  necessary,  as  long  as  anything  is  taken  up  by  the  solvent. 
Unite  the  filtrates  and  evaporate  at  a  gentle  heat  until  a 
dry  mass  is  obtained.  Lastly,  wash  the  residue  repeatedly 
with  absolute  alcohol  and  dry  in  water-bath  until  it  ceases 
to  lose  weight ;  the  residue  is  calculated  as  pure  cane- 
sugar.  (See  also  Scheibler's  method,  page  266.) 

*  "  Report  on  the  Growth  of  the  Beet  in  Ireland,"  British  Blue-Book. 


ESTIMATION  BY  FERMENTATION.  181 

METHOD   BY  FEKMENTATION. 

The  use  of  this  process  is  open  to  many  objections  both 
from  a  want  of  exactness  which  is  inherent  in  it,  but  also 
from  the  length  of  time  required  for  its  execution.  One 
source  of  inaccuracy  is  that  the  fermentation  does  not 
always  give  the  quantities  of  alcohol  and  carbonic  acid  in 
the  normal  proportions  ;  sometimes  a  secondary  fermenta- 
tion takes  place,  with  the  formation  of  lactic  acid  and  other 
bodies  from  which  carbonic  acid  gas  is  not  evolved. 

The  process  may  be  carried  out  in  two  ways — viz.,  I.  By 
the  estimation  of  the  alcohol  formed^  and  II.  By  the  esti- 
mation of  the  carbonic  acid. 

I.  By  Estimation  of  Alcohol.— When  a  solution  of 
cane-sugar  ferments,  according  to  the  best  authorities,  100 
parts  of  the  sugar  give  51.11  parts  by  weight  of  alcohol. 
The  determination  is  conducted  as  follows  :  A  rather  dilute 
solution  of  the  sugar  is  placed  in  a  flask,  and  dry  yeast 
added  in  quantity  from  4  to  5  per  cent,  of  the  liquid,  and 
the  whole  exposed  to  a  temperature  of  from  20°  to  25°  C. 
When  the  fermentation  is  finished,  which  is  in  from  24  to  36 
hours  for  a  moderate  quantity  of  sugar,  the  solution  is  sub- 
mitted to  distillation,  and  the  amount  of  alcohol  contained 
in  the  distillate  is  determined  in  the  usual  way. 

II.  By  the  Estimation  of  Carbonic  Acid.— The  so- 
lution is  placed  in  a  flask  whose  cork  has  two  perforations, 
one  of  which  carries  a  small  glass  tube  just  passing  through 
the  stopper  and  closed  at  its  outer  end  during  the  fermen- 
tation ;  the  other  carries  a  tube  bent  at  a  right  angle  and 
connected  with  a  U-tube  containing  fragments  of  pumice- 
stone  moistened  with  concentrated  sulphuric  acid,  which  in 
turn  is  joined  to  a  second  U-tube  filled  with  chloride  of  cal- 


182  DETERMINATION  OF  CANE-SUGAR. 

cium  in  lumps.  The  proper  quantity  of  yeast  is  added  to 
the  flask,  and  the  whole  system,  consisting  of  flask  and 
tubes,  is  weighed  ;  it  is  then  allowed  to  remain  at  a  tem- 
perature of  20°  to  25°  C.  until  fermentation  has  ceased. 
An  aspirator  is  now  applied  to  the  chloride  of  calcium 
tube,  the  stopper  removed  from  the  glass  tube,  and  a 
current  of  air  drawn  through  the  arrangement,  the 
flask  being  meanwhile  moderately  heated  to  facilitate  the 
disengagement  of  the  gas.  The  U- tubes  serve  to  dry  the 
gas  so  that  no  water  may  escape  during  the  aspiration.  The 
apparatus  is  now  reweighed,  and  the  difference  between  the 
first  and  second  weights  shows  the  quantity  of  carbonic 
acid  produced  during  the  experiment.  100  parts  of  cane- 
sugar  correspond  to  48.89  parts  of  carbonic  acid. 

When  invert  or  grape  sugar  is  present  they  will  have  to 
be  determined  separately,  and  the  amount,  calculated  into 
cane-sugar,  subtracted  from  the  result  given  by  fermenta- 
tion ;  475  parts  cane-sugar  =  500  parts  invert-sugar. 

DETERMINATION   OF  CANE-SUGAR  BY  FEHLING'S   METHOD 
AFTER  INVERSION. 

Acids  have  the  property  of  converting  cane  into  invert 
sugar  in  definite  proportion,  so  that  19  parts  of  the  former 
produce  20  parts  of  the  tatter. 

Execution  of  the  Test. — To  determine  the  cane-sugar, 
1.00  gramme  of  the  substance,  if  of  a  high  tenor  in  sugar, 
and  a  proportionately  larger  quantity  if  the  amount  of 
sugar  is  lower,  is  dissolved  in  about  100  c.  c.  of  water  in  a 
half -litre  flask,  3  c.c.  of  strong  hydrochloric  acid  added, 
and  the  whole  heated  for  twenty  minutes  on  a  water-bath 
to  70°  ;  the  liquid  is  then  nearly  neutralized  with  caustic  or 
carbonated  alkali.  When  the  contents  of  the  flask  have 


ESTIMATION  OF  CANE-SUGAR  BY  INVERSION.  183 

cooled,  the  solution  is  made  up  to  the  mark  and  is  then 
ready  for  testing.  The  method  of  estimating  the  invert- 
sugar  formed  is,  according  to  Fehling,  either  with  Soxh- 
let's  modification  (page  201)  or  after  the  gravimetric 
method  (page  203).  For  work  with  any  pretension  to  ac- 
curacy the  simple  titration  is  quite  inadmissible. 
Calculation. — 

CuO  X  .4307 

Cu     X  .5394  =  cane-sugar. 

Invert-sugar  X  .950  —  cane-sugar. 

When  invert-sugar  is  also  present  in  the  solution  of 
which  the  cane-sugar  is  to  be  determined  by  inversion,  the 
former  is  first  estimated  as  a  separate  operation,  and  then  a 
portion  of  the  original  solution  is  inverted  as  directed 
above,  and  the  total  invert-sugar,  including  that  formed 
from  the  cane-sugar,  is  determined  with  the  copper  liquor. 

An  example  will  indicate  the  calculation  required.  The 
amount  of  invert-sugar  present,  as  found  by  the  direct  test 
with  the  copper  liquor,  is  12.00  per  cent.;  for  inversion 
1.00  gramme  of  the  substance  is  dissolved  to  500  c.c.,  and  of 
this  solution  36  c.c.  are  necessary  to  precipitate  12  c.c.  of 
the  copper  liquor ;  then 

36  X  .002  =  .072  gramme  of  substance  containing  .060 
gramme  invert-sugar,  or  83.33  per  cent. 

83.33 

12.00  less  invert-sugar  originally  present, 


71.33,  which  is  the  figure  representing  the  invert-sugar 
derived  by  inversion  from  the  cane-sugar. 

19  :  20  ::  x  :  71.33  =  67.76  per  cent,  cane-sugar ; 
or,  71.33  X  T%  =  67.76. 


184  DETERMINATION  OF  CANE-SUGAR. 

When  the  oxide  or  metallic  copper  is  weighed,  the  calcula- 
tion is  entirely  similar. 

In  some  cases  the  heating  of  the  sugar  solution  with 
strong  mineral  acid  causes  a  slight  decomposition  of  the 
invert-sugar,  which  is  shown  by  the  liquid  assuming  a 
brown  color.  To  avoid  this  Brunner  recommends  oxalic 
acid  as  the  inverting  agent. 


CHAPTER    VIII. 

DETEEMINATION   OF  DEXTEOSE  AND  INVEET-STTGAE. 

Section  I.  Fettling1  s  Method  and  its  Modifications. 

THE  basis  of  this  method  is  a  qualitative  reaction  for  the 
detection  of  dextrose  in  the  presence  of  cane-sugar,  dis- 
covered by  Trommer,  whose  results  are  summed  up  as  fol- 
lows :  (1)  An  alkaline  solution  of  copper  oxide,  containing 
a  fixed  organic  acid,  as  tartaric,  has  the  oxide  reduced  to 
suboxide  by  dextrose,  and  cane-sugar  under  the  same  cir- 
cumstances is  not  at  all,  or  only  slightly,  affected ;  (2)  cane- 
sugar,  when  inverted  by  acids,  is  converted  into  a  mixture 
of  dextrose  and  levulose,  which  acts  toward  the  alkaline 
copper  solution  precisely  as  grape-sugar  ;  (3)  there  is  a  de- 
finite relation  between  the  amount  of  oxide  reduced  and 
the  sugar.  The  reaction  takes  place  slowly  in  the  cold, 
and  almost  instantly  at  the  boiling  temperature.  By  the 
oxidation  of  grape-sugar  formic,  acetic,  and  oxalic  acids 
are  formed.  According  to  Reichardt,  gummic  acid  is  also 
produced ;  but  this  is  denied  by  Glaus,  *  who,  however, 
found  oxymalonic  acid. 

Barreswill  first  took  advantage  of  Trommer' s  reaction  to 
make  it  the  basis  of  a  quantitative  method  for  the  rapid 
estimation  of  cane  and  grape  sugar.  The  solution  pro- 
posed by  him,  consisting  largely  of  alkaline  carbonates, 
was  found  difficult  to  keep  on  account  of  the  deposition  of 

*Zeits.  fur  Chemie,  1869,  No.  5. 
185 


186      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

oxide  of  copper.  It  was  improved  by  Fehling,*  who  has 
investigated  the  quantitative  relations  of  the  bodies  taking 
part  in  Trommer's  reaction.  He  found  that  one  equivalent 
of  anhydrous  grape  or  invert  sugar  was  capable  of  reduc- 
ing the  oxide  corresponding  to  ten  equivalents  of  crystal- 
lized cupric  sulphate — as  : 

1  eq.  dextrose  10  eq.  cupric  sulphate 

CCH12O6  =  180   :          CuSO4  +5H2O  =  2494. 
This  has  been  confirmed  by  Neubauer.f 

There  are  two  ways  of  proceeding  in  regard  to  the  estima- 
tion of  sugars  by  the  Fehling  process — one  making  use  of 
all  the  refinements  of  more  recent  discovery  and  requiring 
a  considerable  amount  of  time,  being  adapted  for  cases 
where  the  greatest  accuracy  is  required ;  and  the  other 
quickly  and  easily  executed,  but  quite  exact  enough  for 
many  technical  purposes.  It  is  proposed  to  discuss  the 
subject  divided  as  indicated  above. 

Part  I.  The  Method  as  Suited  for  Technical  Work 
—Volumetric. 

Some  recent  researches  have  thrown  doubt  upon  the  con- 
stancy of  the  relation  between  dextrose  and  the  amount  of 
copper  oxide  reduced  by  it  from  alkaline  solution,  wliich 
affects  both  the  volumetric  and  gravimetric  methods.  A 
conformity  with  these  results  would  necessitate  an  altera- 
tion in  the  mode  of  operating,  considerably  lengthening  it. 
These  considerations,  however,  do  not  affect  the  substantial 

*  Ann.  der  Client.  Pharm.,  Ixxii.  106. 

f  Arch,  der  Pharm.,  [2]  Ixxi.  278.  Soxhlet  denies  that  the  relation  between 
the  copper  salt  and  glucose  is  fixed,  but  that  it  varies  according  to  the  circum- 
stances under  which  the  test  is  made,  from  9.7  to  11.1  equivalents  of  copper 
oxide  to  one  of  grape-sugar.  See  results  of  Soxhlet  and  others,  page  201. 


FEELING'S  SOLUTION.  18? 

value  of  Fehling'  s  process  as  ordinarily  carried  out  for  the 
greater  part  of  commercial  work,  such,  as  the  analysis  of 
raw  sugars,  syrups,  etc.,  when  the  tenor  is  not  higher  than 
20  per  cent.  There  are  cases  that  occur  in  commercial 
practice  where  the  greatest  possible  exactness  and  care  is 
required,  and  for  which  no  analytical  refinement  would  be 
misplaced.  The  analyst,  however,  must  form  his  own 
judgment  as  to  the  proper  course  to  pursue  under  any 
given  circumstances. 

Fehling's  Solution. — The  formula  for  this  solution  is 
as  follows  : 

34.64  grammes  pure  cryst.  cupric  sulphate,  dissolved  in  160 

c.c.  dist.  water ; 
150  grammes  neutral  potassium  tartrate,  dissolved  in  600 

c.c.  to  700  c.c.  of  soda  lye  sp.  gr.  1.12  (equivalent 

to  about  90  grammes  of  the  dry  salt). 

The  two  solutions  are  mixed  and  made  up  with  water  to  a 
volume  of  1000  c.c.  at  15°.  Of  this 

10  c.c.  is  equivalent  to  .050  grm.  dextrose  or  invert-sugar ; 
"  "  .0475    "      cane-sugar. 

Fehling' s  solution,  unfortunately,  is  not  very  stable,  de- 
positing oxide  of  copper  in  the  cold,  and  especially  when 
heated  or  exposed  to  light. 

Violette  *  and  Monier  each  give  a  formula  for  a  solution 
which  is  said  to  keep  well,  but  doubtless  that  of  the  latter 
is  less  to  be  recommended  on  account  of  its  strong  alka- 
linity. 
. 

*  Dosage  du  sucre  au  moyen  des  liqueurs  titrees. 


188      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

Violette's   Solution.— 

34.64  grammes  pure  ciyst.  copper  sulphate. 
187  "       tartrate  of  soda  and  potash  (Rochelle  salt). 

78  "       caustic  soda. 

The  copper  salt  is  to  be  dissolved  in  140  c.  c.  of  distilled 
water,  slowly  added  to  a  solution  of  the  tartrate  and  caus- 
tic soda,  and  the  whole  made 'up  to  one  litre  at  standard 
temperature. 

10  c.c.  —  .050    gramme  dextrose  or  invert-sugar. 
"       —  .0475        "         cane-sugar. 

Monier's  Solution. — 

40  grammes  pure  cryst.  copper  sulphate. 
8  chloride  of  ammonium. 

80  acid  tartrate  of  potash  (cream  of  tartar). 

130        "          caustic  soda. 

The  sulphate  is  dissolved  in  160  c.c.  of  water,  the  ammo- 
nium salt  added,  the  solution  mixed  with  the  other  ingre- 
dients dissolved  in  600  c.c.  of  distilled  water,  and  the  whole 
made  up  to  one  litre. 

10  c.c.  =  .0577  gramme  dextrose  or  invert-sugar. 
"      =  .0548  cane-sugar. 

The  ammonium  chloride  furnishes  free  ammonia,  which 
acts  as  a  solvent  for  oxide  of  copper,  thus  preventing  its 
precipitation  on  standing. 

The  investigations  of  several  chemists  *  seem  to  establish 
that  long  boiling  of  cane-sugar  with  a  strongly  alkaline  so- 
lution containing  copper  oxide  causes  a  reduction  of  the 
oxide  in  small  quantity.  But,  however,  if  (1)  the  solution 

*  Loiseau,  Amer.  Chemist,  iv.  291.  Felz,  ibid.,  iv.  113  ;  iii.  313.  Possoz, 
Journ.  des  Fdbr.  des  Sucre,  xiv.  50. 


METHOD  OF  POSSOZ.  189 

is  diluted  sufficiently,  (2)  if  the  reduction  takes  place 
quickly,  and  (3)  if  the  copper  liquor  used  has  merely 
enough  alkali  to  ensure  its  permanence,  either  in  the  cold 
or  at  a  boiling  heat,  the  error  from  this  source  is  too  small 
to  affect  the  results  notably  for  any  purpose  to  which  the 
method  can  be  suitably  applied. 

Possoz's  Solution. — Possoz  recommends  a  copper  li- 
quor which  he  claims  has  no  action  on  cane-sugar  when 
used  according  to  the  directions  given: 

40  grammes  pure  crystallized  copper  sulphate. 
300  tartrate  of  potash  and  soda. 

29       "        caustic  soda. 
150       "        bicarbonate  of  soda. 

The  sulphate  of  copper  is  dissolved  in  150  c.c.  of  water  and 
the  bicarbonate  added.  The  other  salts  are  made  into  a 
solution  with  500  c.c.  of  water,  the  two  solutions  mixed, 
boiled  for  one  hour,  allowed  to  cool,  and  water  added  to 
make  one  litre.  The  resulting  solution  is  allowed  to  stand 
six  months  before  use. 

10  c.c.  =  .0577  gramme  dextrose. 
"      =  .0548        "        cane-sugar. 

The  sugar  solution  to  be  tested  by  this  process  should  be  of 
such  a  concentration  that  .100  gramme  dextrose  or  invert- 
sugar  precipitates  the  copper  from  30  c.c.  of  the  copper 
liquor.  The  estimation  is  made  by  heating  to  70°  C.  with 
a  measured  excess  of  copper  liquor,  filtering,  and  determin- 
ing the  copper  remaining  in  the  filtrate  by  a  suitable 
method  ;  whence  the  amount  reduced  by  the  dextrose  may 
be  calculated. 

The  formula  following  gives  a  cupric  liquor  which  will  be 


190      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

found  to  be  perfectly  permanent ;  used  with  the  necessary 
precautions,  its  action  on  cane-sugar  may  be  altogether  dis- 
regarded for  ordinary  work.  It  is  the  same  as  Violette's, 
except  that  the  proportion  of  alkali  contained  is  somewhat 
altered : 

34.64  grammes  pure  cryst.  copper  sulphate. 
180  "          tartrate  of  potash  and  soda. 

70  "          caustic  soda. 

Dissolve  the  tartrate  and  soda  in  600  c. c.  of  distilled  water, 
and  to  this  add  the  cupric  salt  in  solution,  in  small  quan- 
tities at  a  time,  shaking  after  each  addition  ;  when  a  clear 
liquid  is  obtained  it  is  allowed  to  cool  and  made  up  to  one 
litre. 

10  c.c.  =  .050  gramme  dextrose  or  invert-sugar. 
"       =  .0475       u       cane-sugar. 

Selection  of  Reagents. — The  tartrate  and  caustic  al- 
kali used  may  be  of  the  best  commercial  quality,  the  latter 
as  free  from  carbonate  as  possible.  In  order  to  obtain  a 
copper  salt  containing  rigidly  the  theoretical  amount  of 
oxide,  the  following  procedure  may  be  adopted  :  Procure 
a  thoroughly  reliable  article  of  chemically  pure  crystallized 
cupric  sulphate,  or  make  it  by  recrystallizing  the  commer- 
cial salt,  and  select  the  clear,  well-formed  crystals,  reject- 
ing those  that  are  opaque  and  which  generally  consist  of  a 
more  or  less  wet  aggregate  of  fine  crystalline  material ;  care- 
fully brush  the  selected  pieces  from  all  fine  powder,  and 
pulverize  them,  repeatedly  pressing  the  powder  between 
sheets  of  filter-paper  to  get  rid  of  any  adhering  moisture. 
Preserve  the  salt  thus  prepared  in  a  closely-stopped  bottle 
unifl  it  is  to  be  weighed  out  for  use.  If  pure  sulphate  of 
copper  cannot  readily  be  obtained,  8.804  grammes  pure  me- 


STRENGTH  OF  SUGAR  SOLUTION.          191 

tallic  copper,  precipitated  by  the  battery  or  otherwise,  is 
dissolved  in  nitric  acid,  and  sulphuric  acid,  in  quantity 
slightly  more  than  that  necessary  to  combine  with  the  cop- 
per, is  added ;  the  mixture  is  evaporated  to  drive  off  the 
nitric  acid,  the  free  sulphuric  acid  neutralized  with  caus- 
tic soda,  and  the  copper  sulphate  thus  obtained  is  used  in 
the  preparation  of  the  copper  solution  by  the  above  for- 
mula ;  8.804  grammes  of  copper  is  exactly  the  amount  con- 
tained in  34.64  grammes  of  the  crystallized  sulphate.  Care 
must  be  taken  to  thoroughly  dry  the  precipitated  copper, 
and  at  so  low  a  temperature  that  oxidation  will  not  take 
place.  The  copper  solution  should  be  kept  in  a  blue  glass 
bottle  or  one  blackened  on  the  outside. 

Strength  of  Sugar  Solution. — The  amount  of  sugar 
to  be  determined  varies  greatly  in  different  products  sub- 
mitted to  the  grape-sugar  estimation  ;  it  is  best  to  make 
the  sugar  solution  of  such  dilution  that  from  25  c.c.  to  50 
c.c.  will  precipitate  the  copper  from  10  c.c.  of  the  copper 
liquor ;  the  sugar  solution  should  not  be  much  stronger 
than  this,  as  it  then  becomes  difficult  to  hit  the  end  point 
of  the  reaction  with  sufficient  delicacy. 

Calculation  of  Results — Glucose  Normal. — It  is 
convenient  to  establish  a  standard  strength,  for  the  sugar 
solution,  of  5  grammes  of  the  substance  to  be  assayed  to 
lOOc.c.,  and  this  maybe  called  the  glucose  normal  solu- 
tion. From  the  varying  amounts  of  grape-sugar  contained 
in  the  material  to  be  examined  it  becomes  necessary  to  vary 
from  the  glucose  normal  by  weighing  out  10,  15,  or  20 
grammes  to  100  c.c.  of  volume,  when  the  solution  becomes 
double,  triple,  or  quadruple  normal;  or  to  weigh  £>• 
grammes  of  assay,  and  dilute  to  200  c.c.,  300  c.c.,  or  500 
c.c.,  when  the  solution  is  called  half,  third,  or  fifth  nor- 


192      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

mal.  The  calculation  of  the  results  may  be  greatly 
abridged  in  the  following  way :  The  reciprocal  of  the  num- 
ber of  cubic  centimetres  required  of  the  glucose  normal 
solution  to  precipitate  10  c.  c.  of  the  copper  liquor,  multi- 
plied by  100,  is  the  direct  percentage  of  dextrose  or  invert- 
sugar  sought ;  for 

10  c.c.  copper  liquor  =  .050  gramme  grape-sugar, 

and  the  normal  glucose  solution  contains  in  1  c.c.  —  .050 
gramme  of  the  substance.  Suppose  in  an  experiment  30 
c.c.  of  sugar  solution  is  required  for  10  c.c.  of  copper  solu- 
tion ;  then 

30  X  .050  —  1.50  grammes  of  assay  used,  containing 

.050  gramme  grape-sugar, 
.05 
1.50  =  3.33  per  cent,  grape-sugar; 

the  reciprocal  of  30  is  .0333,  which,  by  displacement  of  the 
decimal  point,  becomes  3.33.  A  table  for  thus  calculating 
percentages  is  appended. 


TABLE. 


193 


TABLE  FOR  CALCULATING  THE  PERCENTAGE  OF  GRAPE  OR  INVERT  9&JGAR  WHEN 

THE  NUMBER  OF  c.c.  USED  REFERS  TO  THE  "  GLUCOSE  NORMAL  SOLUTION." 

(5  grammes  to  100  c.c.} 


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194      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 


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459 

.2179 

488 

.2049 

517 

•1934 

546 

.1831 

575 

•  1739 

431 

.2320 

1  460 

.2174 

489 

.2045 

518 

.1930 

547 

.1828 

576 

.1736 

432 

•2315 

461 

.2169 

490 

.2041 

519 

.1927 

548 

.1825 

577 

•  1733 

433 

.2309 

462 

.2164 

491 

.2037 

520 

.1923 

549 

.1821 

578 

.1730 

434 

.2304 

463 

.2160 

492 

.2032 

521 

.1910 

550 

.I8l8 

579 

.1727 

435 

.2299 

464 

•2155 

493 

.2028 

522 

.1916 

551 

.1815 

|o 

.1724 

430 

.2203 

465 

.2150 

494 

.2024 

523 

.1912 

552 

.1812 

.1721 

437 

.2288 

466 

.2146 

495 

.2020 

524 

.1908 

553 

.i*c8 

#2 

.1718 

438 

.2283 

467 

.2141 

496 

.2016 

.1905 

554 

.1805 

5^3 

.1715 

439 
440 
441 

.2278 
.2273 
.2267 

468 
469 
470 

.2137 
.2132 
.2128 

497 
498 
499 

.2012 
.2008 
.2004 

527 
528 

.1901 
.1897 
.1894 

555 
556 
557 

.1802 
.1798 
•1795 

584 
£ 

.I7I2*""! 

.1709 

.1706 

442 

.2262 

471 

.2123 

500 

.2OOO 

529 

558 

587 

.1703 

443 
444 

•2257 
.2252 

472 
473 

.2119 
.2114 

5Ci 
502 

.1996 

.1992 

530 
531 

iill 

559 
560 

'.Ij8& 

588 
589 

.1700 

.1698 

445 

•2247 

474 

.2110 

5°3 

.1988 

532 

!i8feo 

56l 

.1782 

590 

.1695  i 

446 
447 

.2242 
.2237 

475 
476 

.2105 
.2101 

504 
505 

.1984 
.1980 

533 
534 

.1876 
.1873 

562 
563 

.1779 

.1770 

59i 
592 

448 

.2232 

477 

.2096 

500 

.1976 

535 

.1869 

564 

•  1773 

593 

1686 

449 
450 

.2227 
.2222 

478 
479 

.2002 
.2088 

507 
508 

.1972 
.1968 

536 
537 

.1865 
.1862 

1 

.1770 
.1/67 

594 

595 

.1683 
.1681 

451 

.2217 

480 

.2083 

509 

.1965 

538 

.1859 

.1764 

590 

.1678 

452 

.2212 

481 

.2079 

510 

.1961 

539 

.1855 

566 

.1760 

597 

.1675 

453 

454 

.2207 
.2203 

482 
483 

•2075 
,  .2070 

5" 
512 

•J953 

540 
541 

.1852 
.1848 

569 
570 

•  1757 

•1/54 

598 
599 

.1672 
.1669 

455 

.2198 

484 

.2066 

513 

.1949 

542 

.1845 

571 

•1751 

600 

.1667 

1 

The  use  of  the  table  is  quite  simple.  When  the  volume 
of  sugar  solution  used  is  very  small  or  fractional,  by  a 
change  of  the  decimal  point,  making  a  whole  number,  a 
more  exact  figure  may  be  obtained,  the  operator  always 
knowing  approximately  the  percentage  of  grape-sugar,  so 
as  to  be  able  to  set  down  the  result  correctly.  Thus  an  ex- 
periment gives  4.1  c.c.  of  the  glucose  normal ;  looking  in 
the  table  for  the  percentage  opposite  41,  we  find  it  to  be 
2.44,  which,  by  change  of  the  decimal  point,  gives  24.40 
per  cent,  as  the  true  result.  If  410  is  taken  instead  of  41 
a  still  more  exact  result  is  obtained — namely,  24.39  per 
cent.  In  cases  where  the  strength  of  the  sugar  solution 
varies  from  the  normal,  the  result  of  the  test  in  c.  c.  may  be 
reduced  to  the  standard  by  multiplying  by  2,  3,  or  5  re- 
spectively when  the  half,  third,  or  fifth  normal  solution  is 
used  ;  or  by  dividing  by  2,  3,  or  4  for  the  double,  triple,  or 
quadruple  normal  solution. 


CALCULATION  OF  RESULTS.  195 

Examples  :  I.  5  grammes  of  a  raw  sugar  were  dissolved  to 
300  c.  c. ,  and  on  estimation  it  was  found  that  36  c.  c.  were 
required  for  10  c.c.  of  copper  liquor ;  then  -336  =  12,  and  the 
corresponding  percentage  in  the  table  is  8.33.  II.  20 
grammes  of  cane- juice  made  to  100  c.c.  required  24.6  c.c.; 
hence  24.6  X  4  =  98.4.  Calling  this  98.5,  we  find  from  the 

table  that 

98  corresponds  to  1.02  per  cent. 

and  99        "  "  1.01        " 


The  average  is  98.5  "  1.015      " 

which  is  the  percentage  sought. 

When  the  estimation  of  grape-sugar  is  made  on  the  same 
sample  from  which  the  cane-sugar  is  determined  with  the 
saccharimeter,  it  saves  a  great  deal  of  time  to  have  a 
pipette  graduated  to  deliver  19.21  c.c.  when  the  Soleil- 
Ventzke  saccharimeter  is  used,  and  30.8  c.c.  for  those  hav- 
ing the  normal  weight  of  16.19  grammes.  These  pipettes 
measure  precisely  5  grammes  of  the  original  substance. 
In  this  way,  after  sufficient  of  the  filtered  solution  has  been 
taken  for  polarizing,  f rdm  the  remaining  portion  (free  from 
lead)  the  required  quantity  is  taken  out  with  the  appropri- 
ate pipette  to  make  the  glucose  normal  solution  or  its  multi- 
ples. By  this  method  of  proceeding  one  weighing  suffices 
for  two  determinations,  and  a  further  advantage  is  that  a 
better  average  sample  is  obtained  by  weighing  26  or  16 
grammes,  while  the  glucose  and  cane-sugar  determinations 
are  made  from  identically  the  same  solution. 

When  the  sugar  solution  is  sufficiently  colored  to  inter- 
fere with  the  copper  test,  it  may  be  readily  decolorized  by 
shaking  with  a  very  small  quantity  of  bone-black  and  fil- 
tering. 


196      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

Organic  matter  other  than  sugar  exerts  a  very  slight,  if 
any,  influence  upon  the  results  of  the  invert-sugar  estima- 
tion after  Fehling  *  (see  note  at  the  end  of  the  volume). 

*  It  is  entirely  inadmissible  to  use  a  sugar  solution  containing  lead  in  Fehl- 
ing's  method,  as  the  results  of  experiments  given  below  show.  This  fact  was 
pointed  out  by  H.  C.  Gill  (J.  Chem.  Soc.,  1871,  April),  who  also  suggested  the 
use  of  sulphurous  acid  as  a  precipitating  agent.  Experiments  that  I  have 
made  on  the  subject  confirm  Gill's  results,  and  establish  further  that  the  preci- 
pitation of  the  lead  must  be  very  complete,  as  a  mere  trace  seems  to  interfere  as 
much  with  the  test  as  a  larger  quantity.  For  this  reason  sulphates  are  unsuita- 
ble as  precipitating  agents,  sulphate  of  lead  being  perceptibly  soluble  in  water 
and  sugar  solutions.  The  use  of  sulphurous  acid  is,  however,  not  open  to  this 
objection. 

EFFECT  OF   LEAD    SOLUTION. 

I.  Refined  sugar  containing  4.25  percent,  invert-sugar. 

A  sugar  solution  required  for  10  c.c.  copper  liquor 35.5  c.c. 

The  same,  with  excess  of  lead  solution,  required 48.5     " 

The  same,  with  lead  solution  and  excess  of  Na2S04,  re- 
quired  43.5     " 

II.  Invert-sugar  from  cane-sugar. 

A  solution  to  precipitate  10  c.c.  of  copper  liquor  re- 
quired  '. 53.5  c.c. 

The  same,  with  a  large  quantity  of  Na2S04,  without 

lead,  required 53.6     " 

The  same,  with  lead  solution  and  excess  of  Na2S04, 

required 90        " 

III.  Molasses- sugar  containing  2  86  per  cent,  invert-sugar  : 

A  solution  required  to  precipitate  10  c.c.  copper  liquor,  50.7  c.c. 

The  same,  with  a  large  quantity  of  Na2S04,  required  50.2    " 

The  same,  with  lead  solution  and  excess  of   Na2S04, 
required 68       " 

EFFECT  OF  SULPHUROUS    ACID. 

I.  A  sugar  solution  required  for  10  c.c.  copper  solution  31.2  c.c. 

The  same,  with    5  per  cent.  S02  solution 31.0   " 

"  "20      "  "        "        31.5  « 

"  "30      "  "        "       31.2  " 

"  "50      "  "        "        313   " 

II.  A  solution  of  sugar  required  for  10  c.c.  copper  liquor  30.7  c.c. 

The  same,  with  1  per  cent,  lead  solution 37.5   " 

"  "    1       "  "        "       and    excess 

of  SO,..  ..  32.0  " 


EXECUTION  OF  THE  TEST.  197 

Execution  of  the  Test. — 10  c.c.  of  the  copper  liquor  is 
measured  into  a  porcelain  dish  or  casserole,  diluted  with  its 
volume  of  water,  and  with  a  good  flame  quickly  brought 
to  a  boil.  The  liquid  should  show  no  signs  of  precipita- 
tion by  ebullition.  The  sugar  solution  is  added  from  a 
burette  as  rapidly  as  possible  without  risk  of  running  in 
an  excess.  The  color  changes  from  a  deep,  clear  blue  to  a 
dull  hue,  and  at  the  same  time  the  suboxide  begins  to 
form.  As  the  operation  proceeds  the  red  color  begins  to 
manifest  itself,  and  the  liquid  assumes  a  bluish- violet  tinge, 
in  which  the  red  constantly  increases,  the  shades  passing 
through  bluish  red,  violet  red,  dark  crimson,  and  finally  to 
a  full  crimson,  when  the  copper  is  just  thrown  down.  The 
last  color  changes  to  a  bright  scarlet  as  soon  as  invert-sugar 
or  grape-sugar  is  present  in  excess.  The  experienced  ope- 
rator can  easily  estimate  by  the  color  of  the  boiling  solu- 
tion how  the  operation  is  proceeding,  the  end  point  of  the 
reaction  being  indicated  by  the  full  crimson  color  of  the 
agitated  mass,  without  tinge  of  scarlet,  and  by  the  shade 
of  the  supernatant  liquid  after  the  suboxide  has  settled 
out,  which  should  be  a  clear  pearl  white,  neither  bluish 
nor  yellowish. 

In  order  that  the  end  point  may  be  determined  with 
greater  exactness,  it  is  necessary  to  remove  a  little  of  the 
liquid  in  a  small  pipette,  filter,  acidify  with  acetic  acid, 
and  add  a  drop  of  a  very  dilute  solution  of  potassium  fer- 
rocyanide,  which  will  strike  a  brownish-red  color  as  long 

III.  A  sugar  solution  required 80.7  c.c. 

With  2  c.c.  lead  solution 39.5 

"    2"      "          "       -fexcessSO, 30.5 

"    1   "      "         '«       37.0 

"    1"      "         "       +  excess  S09 33.5 

"    1   "     "         "       +  larger  excess  S02 31.0 


198      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

as  copper  remains  in  solution.     If  the  color  is  very  faint,  a 
practised  operator  can  estimate  the  amount  of  sugar  solu- 

Fig-  25- 


APPARATUS  REQUIRED.  199 

tion  to  be  added,  to  that  actually  ran  in,  to  complete  the  re- 
action. 

Apparatus. — Fig.  25  shows  a  collection  of  apparatus 
suitable  for  carrying  out  the  method  of  testing  described. 
The  arrangement  and  choice  of  implements  can  be  highly 
recommended  where  rapid  work  is  required,  especially 
when  a  number  of  tests  are  made  at  once.  It  consists  of 
a  burette-stand;  two  burettes  provided  with  glass  cocks, 
one  of  50  c.c.  capacity  for  the  sugar  solution,  and  a  second 
of  100  c.c.  for  the  copper  liquor  ;  the  casserole  over  which 
the  burette  delivers  the  sugar  solution  ;  a  pipette  graduated 
to  take  out  5  grammes  from  the  sugar  normal  solution  of  the 
polariscope  ;  small  pipettes  (about  four  inches  long)  for  ob- 
taining a  sample  from  the  casserole  ;  a  rack  for  holding  a 
number  of  3-in.  test-tubes,  funnels  (f  in.),  and  pi- 
pettes, together  with  the  acetic  acid  and  ferrocy- 
anide  of  potassium.  The  latter  are  contained  in 
dropping  or  atropia  bottles,  shown  by  Fig.  26. 
They  have  a  piece  of  sheet  gum  stretched  and 
tied  over  their  tops,  so  that  it  is  only  necessary 
to  press  upon  the  gum  in  order  to  fill  the  tube 
with  liquid. 

When  reliance  is  placed  in  the  disappearance  of  the  blue 

color  alone  as  the  end  point  of  the  test,  the  operation  may 
be  performed  in  a  large  test-tube  held  over  a  sheet  of  white 
paper.  The  color  of  the  liquid,  after  the  precipitate  has 
settled,  is  best  seen  by  holding  the  tube  in  a  slanting  posi- 
tion. This  method  of  carrying  out  the  test  is  not  so  accu- 
rate as  the  one  described,  and  not  quicker  in  execution. 


200      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

Pavy's  Modification  of  the  Volumetric  Method.* 

Dr.  Pavy  has  taken  advantage  of  the  fact  that  caustic 
ammonia  is  a  powerful  solvent  for  suboxide  of  copper.  In 
his  process  he  uses  a  large  excess  of  this  reagent  mixed 
with  the  ordinary  copper  liquor,  so  that  the  reduction 
takes  place  without  precipitation,  the  boiling  solution  be- 
coming decolorized  at  the  same  time.  Under  the  condi- 
tions specified  it  was  found  that  six  molecules  of  cupric 
oxide  are  reduced  by  one  molecule  of  dextrose,  instead  of 
five  molecules  as  in  the  process  of  Fehling  (old  system). 
The  copper  liquor  used  by  Pavy  is  of  the  following 
composition : 

Cupric  sulphate  cryst.,    34.65  grammes  ; 
Potassio-sodic  tartrate,  173  " 

Caustic  potash,  160 

in  one  litre.  120  c.  c.  of  this  solution  is  mixed  with  300  c.  c.  of 
solution  of  ammonia  sp.  gr.  .880,  and  water  added  to  make 
one  litre.  20  c.c.  of  this  corresponds  to  .010  gramme  of 
grape  or  invert  sugar. 

The  test  is  made  in  a  flask  of  about  80  c.c.  capacity, 
with  a  cork  fitted  in  the  neck  carrying  a  glass  tube  dipping 
under  water,  at  the  end  of  the  tube  being  placed  a  piece  of 
rubber  tube,  cut  longitudinally,  so  as  to  form  a  valve  to 
prevent  the  water  from  being  forced  into  the  flask  by  con- 
densation during  a  momentary  stoppage  of  the  operation. 
40  c.c.  of  the  dilute  test  liquor  is  run  into  the  flask,  and 
while  boiling  the  sugar  solution  is  added,  drop  by  drop, 
until  complete  decolorization  is  effected.  The  results  are 
said  to  be  quite  satisfactory »  See  original  papers  (loc.  cit.) 

*  Chem.  News,  xxxix.  77, 197,  249 ;  ibid.,  Steiner,  xl.  139. 


SOXHLET'S  METHOD.  201 

Part  II.  The    Method  as  Suited  for  Exact  Work. 

A.  Volumetric. — SoxhleP  s  Researches. — As  stated  on 
page  186  (note),  Soxhlet,  by  recent  investigations,  has 
demonstrated  that  the  relation  of  dextrose  and  invert-sugar 
to  the  cupric  oxide  reduced  from  alkaline  solution  is  not 
constant,  contrary  to  the  view  formerly  accepted,  but  varies 
within  certain  limits,  according  to  the  circumstances  (mainly 
in  regard  to  dilution)  under  which  the  reduction  takes  place. 
According  to  his  results,  50  c.c.  of  a  1  per  cent,  dextrose 
solution,  or  100  c.c.  of  a  \  per  cent,  solution,  with  the 
undiluted  copper  liquor,  required  for  complete  reduction 
from  101.0  c.c.  to  101.4  c.c.  Fehling's  solution. 

For  the  F.  solution  diluted  with  1  vol.  water,  99.5  c.c.  F.  sol. 

it  U  U  Q        U  U  QO   -I        it  U 

u  u  u  o      u  u        Q^  q     u  u 

a  tt  tt  4     u  u        97  1     u  u 

In  the  case  of  invert-sugar  there  was  required : 

For  the  undiluted  F.  solution 101.2  c.c.  F.  sol. 

For  the  F.  solution  diluted  with  1  vol.  water    99. 5    "       " 
"  "  "  2  u       "          98.2    "       " 

u  u  u  3  u       u          97  3    u       u  * 

These  results  correspond  on  the  average,  for  the  undiluted 
copper  liquor,  to  the  relation  of 

1  eq.  sugar  to  10.1  eq.  CuO, 
and  for  the  fourfold  diluted  solution  : 

1  eq.  sugar  to  9.7  eq.  CuO, 
against  the  relation  of 

1  eq.  sugar  to  10  eq.  CuO, 
according  to  Fehling. 

*  In  later  experiments  these  results  are  varied  from  somewhat. 


202      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

Execution  of  the  Test. — Notwithstanding  these  facts, 
good  results  may  be  obtained,  in  the  determination  of  in- 
vert or  grape  sugar,  if  precaution  is  taken  to  have  the  con- 
ditions in  regard  to  dilution,  and  the  relative  amounts  of 
copper  solution  and  sugar,  the  same  as  indicated  below,  in 
which  case  the  possible  error  is  placed  at  ±  .2  per  cent.  The 
copper  reagent  with  Soxhlet  is  made  of  two  solutions,  viz. : 

No.  1,  consisting  of  34.639  grammes  cupric  sulphate,  dis- 
solved in  water  to  500  c.c.;  and 

No.  2,  of  173  grammes  sodio-potassic  tartrate  (Rochelle 
salt),  dissolved  to  400  c.c.,  mixed  with  100  c.c.  soda- 
lye,  containing  400  grammes  to  the  litre. 

These  solutions  are  kept  separately  and  mixed  in  equal 
volume  when  a  test  is  to  be  made.  To  make  an  estimation, 
a  preliminary  experiment  is  tried  to  find  the  approximate 
strength  of  the  sugar  solution,  and  the  latter  is  diluted 
to  contain  1  per  cent,  of  the  sugar  to  be  determined.  50 
c.c.  of  this  is  heated  to  boiling  for  2  to  4  minutes,  with 
a  quantity  of  the  undiluted  copper  liquor  judged  to  be 
nearly  that  necessary  for  reduction.  The  liquid  mixture  is 
then  thrown  on  a  filter,  and  the  filtrate  tested  for  copper 
with  acetic  acid  and  potassium  ferrocyanide.  If  the 
metal  is  present  a  new  experiment  is  made  with  the  same 
quantity  of  sugar  solution  and  less  copper  liquor,  and  so 
on,  until  in  two  consecutive  experiments,  differing  by  T2¥c.c. 
copper  solution,  the  filtrate  of  one  shows  copper  while  the 
other  does  not.  From  the  quantity  of  copper  solution  cor- 
responding to  the  sugar  the  calculation  can  be  made,  50 
c.c.  of  the  solution  being  equivalent  to  .500  gramme  dex- 
trose or  invert-sugar.* 

*Alfflm,  ScheiUer's  Neue  ZeiL,  1879,  iii.  230.    Soxhlet,  Chern.  Centb.,  1878, 


THE  GRAVIMETRIC  METHOD.  203 

Meissl,*  who  lias  used  this  method  of  estimating  the  in- 
vert-sugar in  raw  sugars  from  the  cane,  states  that  in  an 
experiment  made  by  him  on  a  mixture  containing  known 
quantities  of  cane  and  invert  sugar,  the  former  was  proved 
to  be  without  influence  upon  the  results. 

B.  The  Gravimetric  Method. 

The  investigations  of  Soxhlet  (loc.  cit.)  lead  him  to  the  con- 
clusion that  the  gravimetric  method  for  estimating  sugar  is 
empirical  and  quite  inexact  on  account  of  the  inconstancy 
of  the  relation  between  the  sugar  and  the  copper  oxide  re- 
duced. In  this  particular,  however,  his  views  are  nega- 
tived by  the  recent  exact  experiments  of  Marcker  f  and 
Meissl:}:  (loc.  cit.\  together  with  the  uniform  experience  of 
many  other  chemists. 

The  Estimation. — 25  c.c.  of  Fehling's  solution  (see  for- 

Nos.  14,  15;  Stammer's  Jahresb.,  1878,  178  ;  Jour.  Chem.  Soc.  [abs.],  xxxiv. ; 
Jour.  Pic.  Chem.,  [2]  .21,  227,  317  ;  Jour.  Chem.  Soc.  [abs.],  Oct.,  1880;  Grata- 
ma,  Fres.  Zeit.,  xvii.  155. 

*  Slammer's  Jahresb.,  1879,  180. 

f  Chem.  Cento.,  No.  37;  Stammer's  Jahresb.,  1878, 189. 

%  Meissl  gives  only  a  qualified  approval  of  the  gravimetric  method,  holding 
that  a  close  and  unvarying  relation  must  exist  between  the  quantity  of  precipi- 
tated oxide,  the  reducing  sugar,  and  the  cane-sugar  present — such  a  relation 
which  in  practice  it  would  be  very  troublesome  to  obtain.  He  also  states  that 
the  presence  of  cane-sugar  and  the  length  of  time  the  boiling  of  the  solution  is 
carried  on  have  important  influence  on  the  results.  He  considers  the  process,  as 
ordinarily  carried  out?  to  give  figures  that  are  too  high.  The  whole  question  of 
the  gravimetric  estimation  of  dextrose  and  invert-sugar  is  in  an  unsatisfactory 
condition,  owing  to  the  contradictory  nature  of  the  results  recently  obtained; 
but  the  weight  of  opinion,  principally  founded  on  the  elaborate  investigations 
of  Soxhiet  and  Meissl,  points  to  the  fact  that  the  gravimetric  estimation  is  apt 
to  give  high  results,  especially  in  the  presence  of  cane-sugar ;  and  in  cases  where 
accuracy  is  of  the  highest  importance  it  is  recommended  that  the  tests  be  dupli- 
cated by  this  method,  and  the  volumetric  according  to  Soxhlet,  giving  prefer- 
ence to  the  latter  in  doubtful  cases. 


204      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

mula,  page  190)  are  placed  in  a  100  c.c.  flask  with  the  sugar 
solution  of  known  strength,  but  not  containing  more  than 
.120  gramme  of  the  pure  sugar,  and  the  volume  brought  to 
100  c.c.  The  contents  of  the  flask  are  heated  on  the  water- 
bath  20  minutes,  or  until  a  complete  reaction  is  assured,  care 
being  taken  at  the  end  of  the  operation  that  the  copper  so- 
lution is  in  excess.  Filter  off  the  precipitated  suboxide  ; 
wash  with  hot  water ;  dry  the  filter  and  burn  it  separately 
from  the  precipitate ;  ignite  both  in  a  platinum  boat,  or  a 
Rose  crucible  with  perforated  cover ;  and  finally  reduce 
by  heating  to  redness  in  a  current  of  dry  hydrogen.  After 
complete  reduction,  cool  as  quickly  as  possible  in  hydro- 
gen and  weigh. 

Weight  of  copper  X  .5678  =  dextrose  or  invert-sugar. 

Weighing  as  Oxide. — The  precipitated  copper  may 
also  be  determined  as  oxide  by  igniting  the  suboxide  and 
ash,  after  burning  the  latter  separately,  in  a  platinum  cru- 
cible with  access  of  air  at  a  strong  red  heat,  cooling,  oxi- 
dizing with  a  few .  drops  of  nitric  acid,  again  heating  for 
some  time,  and  finally  weighing.  The  cupric  oxide  multi- 
plied by  .4534  gives  the  invert-sugar  or  dextrose. 

Filter  Ash. — The  filter  generally  obstinately  retains 
some  of  the  salts  of  the  alkaline  solution,  which  no  ordi- 
nary amount  of  washing  seems  to  be  able  to  remove. 
Soxhlet  has  placed  this  very  high — as  much  as  20  milli- 
grammes for  an  ordinary -sized  filter,  though  Marcker  (loc. 
cit.)  has  proved  it  to  be  very  much  less.  It  is  advisable  to 
make  a  special  determination  of  the  ash  of  the  filters  to  be 
used  for  this  method,  on  a  number  through  which  copper 
liquor  has  been  run,  and  the  quantity  adhering  afterward 
washed  out  with  hot  water. 


MOHR'S  METHOD.  205 

Mohr's  Method.*— This  is  said  to  give  results  as  accu- 
rate as  the  above  with  much  less  expenditure  of  time. 
When  moist  stfboxide  of  copper  is  mixed  with  an  acid  so- 
lution of  a  ferric  salt  it  becomes  oxidized  to  cupric  oxide, 
passing  into  solution,  and  reducing  an  equivalent  quantity 
of  the  iron  compound  to  protoxide,  which  may  be  esti- 
mated volumetrically  by  permanganate  of  potassium.  The 
suboxide  formed  by  boiling  the  sugar  solution  with  excess 
of  copper  liquor  is  filtered  off,  thoroughly  washed,  and  an 
acid  solution  of  ferric  sulphate,  or  ammonio-ferric  alum 
free  from  FeO,  is  poured  upon  the  filter  until  the  suboxide 
is  dissolved.  The  filter  is  then  washed  as  long  as  any  iron 
solution  adheres  to  it,  and  the  filtrate,  together  with  the 
washings,  is  titred  with  a  solution  of  potassium  permanga- 
nate containing  3.162  grammes  of  pure  salt  to  the  litre. 

1  c.c.  permanganate  solution  used  =  .0036  gramme  invert 
or  grape  sugar. 

There  have  been  proposed  several  other  processes  for  de- 
termining the  precipitated  suboxide  volumetrically  with 
different  reagents,  and  also  the  modification  of  adding  a 
known  volume  of  copper  liquor  to  the  sugar  solution,  and 
after  the  reaction  estimating  the  amount  of  copper  remain- 
ing dissolved  after  filtering  off  the  suboxide — from  which 
the  amount  thrown  down  as  suboxide  is  found  by  differ- 
ence. None  of  these  devices,  however,  have  any  advan- 
tages over  those  already  given  in  detail. 

*Mohr,  Tithirmethode,  5th  Aufl.,  449. 


206      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

SECTION  II.     DETERMINATION   OF    DEXTROSE    AND    INVERT- 
SUGAR  BY   OTHER  METHODS   THAN   THAT  OF  FEHLING. 

Knapp's  Method.* 

This  is  based  on  the  fact  that  an  alkaline  solution  of  cya- 
nide of  mercury  is  reduced  to  the  metallic  state  by  grape- 
sugar.  It  is  carried  out  as  follows :  10  grammes  of  pure 
and  dry  cyanide  of  mercury  are  dissolved  in  distilled  wa- 
ter, the  solution  mixed  with  100  c.c.  of  caustic  soda-lye  sp. 
gr.  1.145,  and  sufficient  water  to  make  one  litre ;  .400 
gramme  of  the  cyanide  (=40  c.c.  of  the  solution)  at  the 
boiling-point  is  completely  reduced  by  .100  gramme  grape 
or  invert  sugar.  The  titration  is  performed  as  in  Fehling's 
process  :  40  c.c.  of  the  mercurial  solution  is  boiled  in  a 
porcelain  dish,  and  the  sugar  solution  (not  stronger  than  J- 
per  cent.)  is  added  as  quickly  as  possible  until  the  metal  is 
all  thrown  down.  It  is  best  to  make  a  preliminary  experi- 
ment to  find  the  approximate  amount  of  sugar  solution  re- 
quired, and  then  on  the  second  trial  nearly  the  whole 
amount  may  be  run  in  at  once.  To  test  when  the  end 
point  is  attained,  a  drop  of  the  liquid  is  placed  on  a  piece 
of  filter-paper  stretched  over  the  mouth  of  a  beaker-glass 
the  bottom  of  which  is  covered  with  a  strong  solution  of 
sulphide  of  ammonia.  As  long  as  any  mercury  remains  in 
solution  a  brownish  spot  appears  on  the  paper  when  a  drop 
from  the  boiling  solution  is  placed  upon  it.  Perhaps  a  bet- 
ter plan  would  be  to  use  the  alkaline  solution  of  zinc  ox- 
ide, which  may  be  brought  in  contact  with  the  solution  on 
a  porcelain  plate.  While  mercury  yet  remains  in  solution 
a  brownish  coloration  is  produced. 

*  Ann.  der  Chem.  Pharm.,  May,  1870  ;  Amer.  Chemist,  i.  118. 


SACHSSE'S  METHOD.  207 

Knapp,  Lenssen,*  and  Soxhlet,  who  have  carefully  exa- 
mined the  method,  recommend  it. 

Sachsse's  Method. 

A  standard  solution  is  made  by  dissolving  18  grammes  of 
pure,  dry  mercuric  iodide  in  water  with  the  aid  of  25 
grammes  potassium  iodide,  adding  to  the  liquid  80  grammes 
of  caustic  potash  and  water  to  make  one  litre.  40  c.c.  of 
the  solution,  containing  .72  gramme  Hgl,  is  equivalent  to 
.1342  gramme  dextrose  and  to  .1072  grm.  invert-sugar. 

For  the  estimation,  40  c.c.  of  the  standard  solution  are 
boiled,  and  the  sugar  solution  of  known  strength  added  until 
all  of  the  metal  is  precipitated.  This  point  is  ascertained 
by  bringing  a  drop  of  the  solution  in  contact  with  sulphide 
of  ammonia  on  a  piece  of  Swedish  filter-paper,  or  by  an 
alkaline  solution  of  zinc  oxide,  both  of  which  reactions 
give  rise  to  brownish  precipitates  or  colorations  with  so- 
lutions of  mercuric  salts. 

This  process  is  also  based  on  the  reduction  of  mercury 
to  the  metallic  state  by  the  sugar  present.  Heinrich,f 
Meissl,  J  and  Soxhlet  §  recommend  it  as  giving  results 
closely  accordant  with  those  by  Fehling's  method. 

Estimation  of  Dextrose  and  Invert-Sugar  in  the 
presence  of  each  other. 

On  account  of  the  peculiarity  of  Sachsse's  method,  in 
that  dextrose  and  invert-sugar  have  distinctly  different 
reducing  constants  for  the  alkaline  solution  of  mercuric 

*  Fres.  Zeitschrift,  No.  4, 1870.         J  Ibid.,  1879,  178. 

f  Stammer's  Jahresb.,  1878, 195.        §  Journ.  Chem.  Soc.,  Oct.,  1880. 


208      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

iodide,  it  is  possible,  by  a  combination  of  it  with  Fehling's 
process,  to  determine  dextrose  and  invert-sugar  in  the  same 
solution.  An  example  will  illustrate  the  necessary  steps  of 
the  operation  :  25  c.c.  of  sugar  solution  was  found  to  reduce 
40  c.c.  =  .72  gramme  mercuric  iodide,  of  the  Sachsse  solu- 
tion, while  the  same  volume  contained,  according  to  the 
copper  test,  .125  gramme  of  the  total  sugars ;  then,  call- 
ing the  dextrose  x  and  the  invert-sugar  ?/,  we  get  the 

equation : 

#  +  ?/  =  . 125     (I) 

But  as  .1342  gramme  dextrose  and  .1072  gramme  invert-sugar 

72 
each  reduce  .72  gramme  Hgl,  we  havea?  X    '    .    —  5.36  #,  and 

72 
V  X  -— ^  =  6.70  y  ;  whence 

5.36  x  +  6.70  y  =  .72    (2) 

On  combining  these  equations  the  values  of  x  and  y  may 
be  readily  obtained.  Should  x  or  y  be  found  equal  to  0, 
it  indicates  that  the  corresponding  sugar  is  not  present. 

Cane-sugar  in  mixture  with  the  other  two  bodies  may 
also  be  estimated,  where  there  are  no  foreign  reducing  sub- 
stances present,  by  determining  the  dextrose  and  invert- 
sugar  as  above,  and  then  inverting  with  acids  and  estimat- 
ing the  amount  of  invert-sugar  formed  from  the  cane-sugar, 
by  the  copper  method  ;  the  result,  multiplied  by  the  factor 
.95,  gives  the  saccharose  originally  in  the  solution. 

Estimation  of  Levnlose  and  Dextrose  in  the  pre- 
sence of  each  other  (a  combination  of  the  optical  with 
Fehling's  method). — According  to  Neubauer,*  the  angular 
rotatory  power  in  a  tube  100  mm.  long,  at  14°  C.,  of 
Dextrose  is  [a]  j  =  53.1°  Levulose,  [a]  j  =  100°. 

Rotation  constant,  1883.3.  Rotation  constant,  1000. 


*  Neubauer,  Ber.  Chem.  GeselL,  1877,  827. 


ESTIMATION  OF  LEVULOSE  AND  DEXTROSE. 


209 


The  following  table  shows  the  angular  rotations  of  sugar 
solutions  at  14°  C.  in  a  100  mm.  tube : 


Per  cent. 

Levulose. 

Dextrose. 

I 

Corresponding  rotatory  power 

—  1° 

-     .531° 

2 

—  2° 

-  1.062° 

3 

-3° 

-  1-593° 

4 

—  4° 

-  2.124° 

5 

5Q 

-  2.655° 

6 

—  6° 

-  3.186° 

7 

-7° 

-3.7I70 

8 

—  8° 

-1-  4-248° 

9 

—  9° 

+  4-779° 

Estimate  the  total  sugars  by  Fehling's  method,  and  also 
make  an  observation  with  the  saccharimeter  at  14°  C.,  in  a 
100  mm.  tube,  the  result  being  set  down  in  angular  degrees. 
As  an  example,  suppose  a  solution  containing  15  per  cent. 
of  total  sugars  has  a  rotation  of  —  5.202° ;  15  per  cent, 
levulose  corresponds  to  a  rotation  of  — 15°.  The  difference 
between  this  and  the  actual  rotation  is  (—  15°)  —  (—  5.202) 
=  —  9.798°.  This  difference  is  caused  by  the  dextrose  pre- 
sent, and  as  the  algebraic  difference  between  the  rotation 
constant  of  levulose  and  dextrose  (2883.3)  is  to  the  rotation 
constant  of  dextrose  (1883.3),  so  is  the  difference  between 
the  calculated  and  found  rotations  (—  9.798°)  to  the  quan- 
tity of  dextrose  present — as, 

2883  :  1883.3  ::  9.798  :  x 
x  ~  6.4  per  cent,  dextrose. 
15  per  cent.  —  6.4  per  cent.  =8.6  per  cent,  levulose.* 


*  Apjohn  (Chem.  News,  xxi.  86)  and  Dupre  (Chem.  News,  xxi.  97)  give  pro- 
cesses for  estimating  cane-sugar,  dextrose,  and  levulose  in  the  presence  of  each 
other,  consisting  of  combinations  of  the  optical  and  Fehling's  methods. 


OIQ      DETERMINATION  OF  DEXTROSE  AND  INVERT-SUGAR. 

Gentele's  Method.* 

An  alkaline  solution  of  potassium  ferricyanide,  when 
heated  with  grape  or  invert  sugar,  is  reduced  to  ferrocyan- 
ide,  and  the  strongly  yellow  solution  is  wholly  or  partially 
decolorized.  A  standard  solution  is  prepared  by  dissolving 
109.8  grammes  pure  potassic  ferricyanide  and  55  grammes 
caustic  potash  in  water,  and  diluting  to  one  litre : 

10  c.c.  of  this  solution  —  .010  cane-sugar ; 

.01053  grape  or  invert  sugar. 

40  c.c.  of  the  standard  solution  is  heated  in  a  porcelain 
dish  to  70°  to  80°,  and  the  sugar  solution  slowly  added 
until  the  color  is  discharged. 

This  process  has  chiefly  an  historical  interest. 

*  Dingkr's  Polyt.  Journal,  clii.  68,  130. 


CHAPTER  IX. 

ANALYSIS  OF  RAW   SUGAK. 

Composition  of  Raw  Sugars. — Raw  sugar  as  obtained 
from  various  sources  is  a  mixture,  of  which  the  leading 
element  is  cane-sugar;  the  different  constituents  may  be 
classified  as  follows : 

1.  Cane-sugar.  4.  Moisture. 

2.  Invert-sugar.  5.  Organic  matters  not  sugar. 

3.  Salts.  6.  Insoluble  constituents. 

The  cane-sugar  exists  in  three  forms — viz. :  (I)  actually 
crystallized ;  (2)  that  capable  of  crystallizing,  but  held  in 
solution  by  the  moisture  present ;  and  (3)  that  which  is  in- 
capable of  crystallizing,  though  chemically  identical  with 
crystallizable  cane-sugar ;  it  is  distinguished  from  the  latter 
by  being  soluble  in  alcohol  saturated  with  cane-sugar.  The 
non-crystallizable  cane-sugar,  with  the  invert-sugar  and 
the  other  soluble  impurities,  form  the  molasses,  which, 
with  that  formed  in  the  process  of  refining,  is  part  of  the 
yield  of  the  refiner. 

The  salts  are  organic  or  inorganic  ;  the  former  consist  of 
the  bases  potassa,  soda-lime,  magnesia,  and  iron  oxide 
united  with  the  organic  acids,  acetic,  succinic,  malic,  citric, 
oxalic,  tartaric,  aconitic,*  aspartic,f  pectic,  metapectic,  lac- 
tic, proprionic,  butyric,  formic,  glucic,  apoglucic,  humic, 
ulmic,  and  melassic  ;  the  latter,  with  the  same  bases,  are 

*  Has  been  found  only  in  raw  cane-sugar  and  juice,    f  Peculiar  to  beet-sugar. 

211 


212  ANALYSIS  OF  RAW  SUGAR. 

chlorides,  sulphates,  phosphates,  silicates,  carbonates,  and 
nitrates.  Saccharates  of  lime  and  potash  are  also  often 
present,  especially  in  raw  beet-sugars. 

The  organic  matters  not  sugar  are :  I.  The  alkaloids — 
betaine,*  asparagine,*  and  triethylamine  ;  II.  Nitrogenous 
organic  matters — albumen,  legumine,  and  ferments  or  ex- 
tractive matters ;  III.  Non-nitrogenous  organic  matters- 
cellulose,  gum  and  fatty  bodies,  pectose,  pectin,  parapec- 
tin,  essential  oils,  mannite,  alcohol,  starch,  and  coloring 
matter  consisting  for  the  most  part  of  caramel  and  its  deri- 
vatives. 

All  of  these  bodies  are  not  found  in  any  one  sample  of 
raw  sugar  ;  many  are  peculiar  to  raw  beet-sugars,  not  being 
found  in  those  derived  from  the  cane. 

Insoluble  matters.  These  are  principally, sand  and  clay 
with  accidental  mechanical  impurities ;  also  fine  particles 
of  fibre  from  the  cane  often  occur  in  raw  sugars,  giving  the 
solution  a  muddy  appearance. 

Sampling. — Much  depends  upon  the  proper  taking  of 
the  sample  as  well  as  its  preservation.  The  sampling  from 
the  original  packages  is  evidently  not  in  the  province  of  the 
chemist,  and  must  be  left  to  the  experience  and  intelligence 
of  the  sampler,  and  the  business  customs  which  sometimes 
control  this  operation.  The  chemist  should,  however, 
when  practicable,  receive  from  two  to  five  pounds  of  each 
lot  to  be  tested,  representing  as  closely  as  possible  the 
larger  sample  first  taken  ;  this,  if  containing  lumps,  should 
have  them  well  broken  up  and  the  whole  carefully  mixed. 
The  average  sample  thus  obtained  is  preserved  in  a  tightly- 
stopped,  wide -mouthed  bottle,  and  from  this  the  various 

*  Peculiar  to  beet-sugar. 


POLARIZATION.  213 

portions  should  be  weighed  out  for  analysis.  It  is  impor- 
tant to  have  the  bottle  well  corked,  as  in  ordinary  states  of 
the  atmosphere  raw  sugar  loses  its  water  very  rapidly  by 
evaporation,  though  when  the  air  is  damp  the  reverse 
may  take  place,  and  moisture  be  absorbed,  thus  vitiating 
the  analysis  in  its  most  important  item — i.e.,  the  cane- 
sugar. 

ESTIMATION   OF  THE   CANE-SUGAR. 

This  determination  is  made  by  the  optical  saccharimeter, 
and  though  the  choice  of  any  of  those  described  in  the  pre- 
ceding pages  is  open  to  the  operator,  for  the  sake  of  con- 
venience the  description  in  this  section  is  based  upon  the 
supposed  use  of  the  Soleil- Ventzke  instrument ;  this  remark 
will  also  apply  to  the  matter  in  relation  to  the  use  of  polar- 
izing apparatus  in  other  sections  of  this  work. 

The  Weighing. — The  normal  quantity,  26.048  grammes., 
is  weighed  with  the  requisite  accuracy  into  a  convenient- 
sized  German- silver  dish  of  the  F'g-  27- 
form  shown  in  Fig.  27,  provided 
with  a  projecting  lip  so  that  it  may 
be  adapted  to  pouring  into  the 
neck  of  the  measuring-flask ;  the 
dish  has  a  counterpoise  weight. 
There  is  also  a  normal  (26.048  grammes)  and  one-half  nor- 
mal weight.  The  balance  to  be  used  should  not  be  too 
fine,  as  much  time  would  be  lost  in  weighing,  on  account  of 
the  care  necessary  to  avoid  injury  to  it,  as  well  as  the  slow- 
ness with  which  such  balances  swing.  A  strong,  well-made 
instrument  with  a  rather  short  beam,  and  capable  of  quick 
weighing  to  within  .010  gramme  of  the  truth,  is  in  every 


214  ANALYSIS  OF  RAW  SUGAR. 

way  suitable  ;  a  good  apothecaries'  balance,  accurate  to  the 
limit  specified,  does  very  well. 

The  Execution  of  the  Test. — When  the  assay  is 
weighed,  about  50  c.c.  of  water  is  poured  upon  it,  and  by 
means  of  a  thick  glass  rod  with  a  blunt  end  the  mixture  is 
stirred,  any  lumps  present  being  at  the  same  time  crushed, 
until  the  greater  part  of  the  sugar  is  dissolved.  By  allow- 
ing the  contents  of  the  dish  to  settle  a  moment,  the  solu- 
tion may  be  readily  poured  off  into  the  flask,  leaving  the 
undissolved  residue  of  sugar  entirely  in  the  dish.  A 
second  portion  of  water  is  added,  and  so  on  until  the  sugar 
is  completely  dissolved,  and  the  dish  rinsed  out  into  the 
graduated  flask.  There  is  little  advantage  to  be  obtained 
in  the  use  of  hot  water,  except  in  the  case  of  crystal- 
sugars,  as  the  time  required  to  cool  the  solution  to  the  tem- 
perature of  the  operating-room  is  about  equal  to  that  saved 
by  using  heated  water.  A  good  arrangement  for  holding 
the  water  to  be  used  in  the  tests  is  to  have  it  in  a  bottle 
placed  on  a  high  shelf,  and  furnished  with  a  syphon  passing 
through  the  cork,  hanging  down  the  outside  within  conve- 
nient reaching  distance  of  the  operator.  The  syphon  is 
kept  filled  with  water,  the  lower  portion  consisting  of  a 
rubber  tube,  the  end  of  which  is  closed  by  a  spring  clamp 
(Fig.  28).  After  all  the  rinsings  of  the  weighing- capsule 
have  been  added  to  the  flask,  the  solution  of  basic  acetate 
of  lead  or  other  clarifying  agent  is  poured  in,  and  the 
flask  filled  with  water  until  the  lowest  portion  of  the  menis- 
cus, or  curve  formed  by  the  liquid  in  the  neck,  is  just  tan- 
gent to  the  graduation-mark.  The  solution  is  then  well 
shaken,  a  part  of  its  contents  thrown  away,  a  little  bone- 
black  added,  shaken  again,  and  the  mixture  filtered.  Care 
must  be  taken  that  the  temperature  of  the  liquid  does  not 


POLARIZATION. 


215 


differ  much  from  that  of  the  operating-room  throughout 
the  manipulations,  as  an  alteration  in  the  volume  of  the 
sugar  solution  is  attended  with  a  corresponding  change  in 
the  amount  of  sugar  as  shown  by  the  polarizing  apparatus. 

Fig.  28. 


Fig.  23. 


The  quantity  of  lead  solution  to  be  used  must  be  left 
largely  to  the  judgment  of  the  operator,  due  regard  being 
paid  to  the  remarks  pp.  165,  166.  Always  employ  the 
least  amount  with  which  a  good  reading  in  the  sacchari- 
meter  may  be  assured ;  but  not  too  little,  for  nothing 
is  gained  by  attempting  to  make  an  observation  with 
a  dark  solution.  When  from  insufficient  decoloriza- 
tion  a  filtrate  is  obtained  too  dark  for  reading,  a  new  por- 


216  ANALYSIS  OF  RAW  SUGAR. 

tion  of  the  sugar  should  be  weighed  and  the  test  repeated, 
or  the  filtrate  from  the  first  solution  may  be  treated  with  a 
fresh  portion  of  bone-black  and  refiltered.  The  addition  of 
a  few  drops  of  alum  solution  after  the  lead  salt  often 
greatly  increases  the  decolorizing  effect.*  See  page  164. 

Any  suitable  arrangement  for  filtration  may  be  adopted. 
A  very  good  one  is  shown  in  Fig.  29.  A  is  a  cylinder  of 
thick  glass  135  mm.  high  and  27  mm.  internal  diameter. 
The  funnel  is  of  prdinary  glass,  78  mm.  in  diameter  at 
top,  and  of  a  size  to  fit  a  filter  150  mm.  diameter.  It  is 
scarcely  necessary  to  say  that  filter,  funnel,  and  cylinder 
should  be  perfectly  clean  and  dry  before  use. 

When  an  estimation  of  the  glucose  is  to  be  made,  by 
taking  out  a  portion  of  the  solution  made  up  to  100  c.c. 
for  polarizing,  as  recommended  on  page  195,  the  above 
method  of  procedure  is  modified  somewhat.  Instead  of 
adding  the  lead  to  the  solution  before  it  is  made  up 
to  the  mark,  this  is  done  without  any  such  addition, 
the  solution  shaken,  and  from  the  lead-free  liquid  19.2 
c.c.,  or  any  other  volume  equivalent  to  5  grammes 
of  the  original  substance,  is  taken  in  a  suitably  gradu- 
ated pipette,  and  diluted  for  the  glucose  determination. 
The  remainder  of  the  sugar  normal  solution  is  poured 
into  a  50  c.c.  flask  (after  rinsing  it  out  with  a  portion  of 
the  same  solution)  to  the  mark,  a  measured  volume  of  lead 
solution  added  from  a  graduated  pipette,  and  a  correction 
added  to  the  polariscopic  reading  corresponding  to  the 
amount  of  dilution  caused. 

It  is  to  be  recommended  that  the  long  tube  of  200  mm. 

*  It  has  been  asserted  that  the  presence  of  ammonia  or  ammoniacal  salts  in 
the  sugar  liquid  causes  an  error,  owing  to  the  formation  of  a  precipitate  of 
sugar  and  acetate  of  lead. 


POLARIZATION.  217 

should  be  used  whenever  it  is  possible.  For  work  demand- 
ing ordinary  care  it  is  generally  preferable,  in  the  case  of 
dark  solutions  obtained  by  insufficient  decolorization,  to 
weigh  out  a  new  portion  of  the  sugar,  and  use  more  bone- 
black  and  lead,  than  to  employ  the  short  or  100  mm.  tube 
with  the  attendant  errors  of  multiplication.  The  observa- 
tion-tubes, as  well  as  the  caps  and  plates,  should  be  scru- 
pulously cleaned  after  use,  by  washing  and  drying  with  a 
soft  rag  or  chamois-skin,  both  inside  and  outside.  Air- 
bubbles  in  the  flask,  which  make  it  difficult  to  fill  the 
liquid  exactly  up  to  the  mark,  may  generally  be  prevented 
from  making  their  appearance  by  adding  the  solution  from 
the  weighing-capsule  gently  along  the  neck  and  side  of  the 
flask,  and  the  lead  solution  in  the  same  manner.  The  air- 
bubbles,  if  present,  may  be  readily  removed  by  allowing  a 
little  ether  vapor  to  flow  into  the  measuring-flask  from  an 
open  bottle,  or  by  the  addition  of  a  drop,  and  blowing  off 
the  excess  of  the  vapor.* 

ESTIMATION   OF  THE    INVERT-SUGAR. 

This  determination  is  made  according  to  the  methods 
given  in  chapter  viii. 

ESTIMATION    OF    THE  WATER. 

The  moisture  of  raw  sugar  is  determined  by  drying  at 
such  a  temperature  as  will  drive  off  all  the  water  in  a  rea- 

*  There  has  been  a  method  proposed  in  France  for  the  estimation  of  cane- 
sugar  in  raw  sugar,  known  as  the  four-fifths  method,  and,  I  believe,  used  to 
some  extent  in  commercial  analysis.  It  consists  in  taking  four-fifths  of  the 
ash  as  the  number  expressing  organic  matter  not  sugar.  The  sum  of  this— the 
ash,  water,  and  glucose — subtracted  from  100,  represents  the  cane-sugar.  The 
method  is  not  worth  mentioning,  except  as  a  curious  example  of  the  aberra- 
tions to  which  the  human  mind  is  subject. 


218  ANALYSIS  OF  RAW  SUGAR. 

sonable  time  without  decomposition.  The  difference  in 
weight  of  the  sugar,  plus  the  containing  vessel,  before  and 
after  desiccation,  gives  the  amount  of  water.  Two  or 
three  grammes  of  sugar  are  weighed  on  a  tared  watch-glass 
and  placed  in  the  drying  apparatus.  When  the  desicca- 
tion is  completed  the  watch-glass,  with  contents,  are  re- 
weighed.  Glasses  sixty  millimetres  in  diameter  are  of  con- 
venient size.  They  may  be  numbered  by  scratching  on 
them  with  a  hard  file,  and  a  memorandum  of  the  corre- 
sponding tares  kept  posted  up  near  the  balance. 
Example  : 

Watch-glass  +  sugar  before  drying,  10.256    10.256 
"  8.120 


Raw  sugar 2.136 

-f-  sugar    after   drying,  10.153 


Loss,  equivalent  to  water  ............  .103 

.103X100 

=  4.82  per  cent,  water. 


The  sugars  should  be  weighed  as  quickly  as  possible,  and 
some  varieties,  notably  large-grained  refined  sugars  and 
centrifugals,  ought  to  be  enclosed  between  two  watch- 
glasses,  as  they  alter  so  rapidly  by  reabsorption  after  dry- 
ing that  it  is  sometimes  difficult  to  get  a  correct  weighing 
in  the  ordinary  way.  The  heat  of  the  water-bath  oven  is 
inadmissible  as  a  means  of  desiccation  when  the  analyses 
are  made  for  commercial  purposes,  as  the  time  necessary 
for  a  reliable  result  is  much  too  great.  An  accurate  esti- 
mation in  this  way  can  only  be  made  by  drying  with  re- 
peated weighings  until  the  last  two  closely  approximate 
each  other.  The  time  required  for  this,  as  my  experi- 


ESTIMATION  OF  WATER.  219 

ments  *  show,  is  too  long  to  make  the  results  of  the  test 
available  commercially. 

The  drying  is  best  effected  in  an  air-bath  at  a  tempera- 
ture of  110°  C.  The  time  required  varies  with  the  kind  of 
sugar  operated  upon ;  for  dry  sugars  comparatively  free 
from  syrup  a  much  less  time  will  be  sufficient  than  for  the 
moist,  low-grade  products  of  the  refinery  or  plantation. 
No  exact  rule  can  be  given,  but,  on  the  average,  good  quality 
of  beet  and  refined  sugars,. centrifugals  or  crystal- sugars, 
good  and  fair  muscovado,  good  Manillas,  Javas,  and  other 
similar  sugars,  will  lose  their  moisture  in  from  two  to  three 
hours,  while  lower  grades,  such  as  domestic  molasses  and 
low  refinery  products,  Chinese  and  such  sugars,  ought  to 
be  dried  considerably  longer,  though  not  too  long,  for  it  is 
an  observed  fact  that  impure  sugars  are  altered  in  compo- 
sition, attended  with  loss  in  weight,  by  very  long  contin- 
ued heating,  even  at  a  temperature  as  low  as  95°. 

For  very  syrupy  sugars  and  melados  it  becomes  neces- 
sary to  dry  with  the  addition  of  sand.  The  operation  is  con- 

*  The  leading  authorities  attach  too  little  importance  to  the  fact  that  the 
water  in  raw  sugar  exists  as  a  component  of  a  dense  syrup,  and  consequently 
the  last  portions  of  water  resist  the  desiccation  with  great  obstinacy.  As  an 
average  of  many  hundreds  of  dryings  at  95°  C.  (the  temperature  of  the  water- 
bath  oven),  I  find  that  the  following  times  are  necessary  for  the  complete  desic- 
cation of  such  sugars  (cane)  as  occur  in  the  markets  of  this  country  : 
(Quantity  dried  of  each  kind,  about  two  grammes.) 

Centrifugals 9    hours. 

Ordinary  muscovados 3£ 

Low  "  8 

Domestic     molasses      sugar, 
made  fr.  W.  I.  molasses. ...          40  (alteration). 

Manillas 3  to  4 

Melado  in  sand 16 

A  refined 7 

5  to  6 
40 


C      "      /  \.. 

-Q      ,<      (lowest  product  I 


220 


ANALYSIS  OF  EAW  SUGAR, 


ducted  as  follows :  Weigh  in  a  good- sized  watch-glass  or 
metal  dish  a  small  glass  rod  and  about  ten  grammes  of 
clean,  coarse  sand  which  has  been  ignited  and  preserved  in 
a  tightly-closed  bottle  ;  after  the  combined  tare  is  taken, 
add  about  two  grammes  of  the  substance  to  be  examined, 
and,  after  weighing  again,  carefully  mix  with  the  rod, 

Fig.  30, 


moistening  with  a  few  drops  of  alcohol,  so  that  the  assay  is 
thoroughly  and  evenly  mixed  with  the  sand  and  none  of 
the  latter  is  lost ;  the  rod,  after  the  stirring,  is  allowed  to 
remain  in  the  dish  and  is  weighed  with  it. 

The  best  method  of  drying  syrupy  sugars,  whether  with 
sand  or  not,  is  in  a  vacuum  at  90°  C.,  as  not  only  is  the 


ESTIMATION  OF  MOISTURE.  221 

operation  shortened,  but  the  alteration  of  the  sugar  by  heat 
is  reduced  to  a  minimum.  Scheibler  has  proposed  an  ap- 
paratus for  drying  in  vacuo.*  Sugars  that  are  nearly  free 
from  in  vert- sugar,  such  as  high-grade  refined  and  crystal 
raw  sugars,  may  be  safely  dried  in  the  ordinary  way  at  120°; 
and,  indeed,  that  temperature  is  often  necessary  to  com- 
plete the  drying  in  a  reasonable  time. 

Fig.  30  shows  the  air-bath  furnished  with  a  Bunsen  regu- 
lator, whereby  the  flow  of  gas  may  be  made  so  that  any  de- 
sired temperature  may  be  kept  constant ;  the  gas  enters  at 
a.  If  the  temperature  is  too  high  the  mercury  in  the  bulb 
of  the  regulator  rises  and  partially  cuts  off  the  flow  of  gas  ; 
on  the  contrary,  when  the  temperature  in  the  bath  becomes 
lowered,  the  mercury  recedes  and  the  supply  of  gas  is  in- 
creased. In  this  way  the  heat  may  be  kept  pretty  equable 
as  long  as  the  pressure  of  the  gas  remains  the  same.  The 
samples  to  be  dried  are  placed  on  a  perforated  shelf  raised 
some  distance  above  the  bottom,  and  the  bulb  of  the  ther- 
mometer should  nearly  touch  the  former.  Gas-regulators 
are,  however,  often  unsatisfactory  in  practice  ;  generally 
no  difficulty  will  be  encountered  in  maintaining  a  constant 
temperature,  without  a  regulator,  with  an  air-bath  modi- 
fied from  the  one  shown  in  Fig.  30  by  being  enclosed  below 
with  a  sheet-copper  box  having  a  door  for  the  purpose  of 
lighting  the  Bunsen  burner;  the  whole 'arrangement  may 
be  screwed  against  the  wall  in  a  place  sheltered  as  much  as 
possible  from  draughts.  With  a  little  experience  in  regu- 
lating the  size  of  the  flame,  this  apparatus  gives  excel- 
lent results. 

The  Balance. — The  weighing  apparatus  suitable  for  the 

*  Stammer's  Jahresb.,  1870,  199. 


222  ANALYSIS  OP  RAW  SUGAR. 

estimation  of  water,  ash,  etc.,  should  be  accurate  to  .0005 
gramme,  and  not  too  slow  in  movement. 

ESTIMATION   OF   THE  ASH. 

The  ash  of  raw  sugar  represents  its  fixed  mineral  consti- 
tuents, and  is  a  part  of  the  salts  present  ;  these  salts  are 
combinations  of  organic  and  inorganic  acids,  and  radicals, 
with  various  bases.  When  the  sugar  is  incinerated,  the 
organic  matter,  including  the  sugar,  is  oxidized,  and  a 
part  of  the  carbonic  acid  formed  unites  with  the  alkaline 
and  earthy  bases,  producing  carbonates,  which,  together 
with  sulphates,  chlorides,  silicates,  etc.,  constitute  the  ash. 
The  different  combinations,  and  their  proportions  relative 
to  each  other,  vary  much  according  to  the  conditions — viz. : 
1.  The  source  of  the  sugar,  whether  from  the  cane,  the 
beet,  or  of  any  other  origin.  2.  The  character  of  the  soil, 
climatic  conditions,  manures,  and  the  process  of  manufac- 
ture. This  last  item  will  of  itself  furnish  a  wide  range 
of  variation,  as  chemicals  are  in  use  at  the  place  of 
manufacture  which  in  many  cases  remain  in  the  raw  pro- 
ducts, and  necessarily  modify  their  saline  content.  What 
might  be  called  the  normal  asJi  of  raw  sugars,  is  that  from 
sugars  in  which  no  chemical  has  been  used  in  the  course  of 
manufacture,  except  lime. 

The  ashes  of  beet  and  cane  sugars  differ  materially  ;  in  the 
former  there  is  a  large  preponderance  of  the  salts  of  potas- 
sium and  sodium,  while  the  latter  are  characterized  by  a 
much  smaller  quantity  of  alkaline,  but  more  lime- salts  and 
silica.  The  insoluble  impurities,  such  as  clay,  sand,  etc.,  are 
more  common  in  cane  than  in  beet  sugars.  The  following 
analyses  give  the  composition  of  raw  cane  and  beet  sugar 
ash : 


ANALYSES  OF  SUGAR-ASH.  223 

BEET-SUGAR  ASH.     AVERAGE  COMPOSITION. 

I.  Carbonates  of  potassium  and  sodium 82.20 

Calcium  carbonate 6. 70 

Potassium  and  sodium  sulphates  and  sodium  chloride.     11.10 

100.00 
— (Monier.) 

By  simple  By  addition 

incineration.  of  SO,jH2. 

II.  Sulphuric  anhydride 17.63  58.38 

Chlorine 4.48                   * 

Silica , 0.72  .72 

Carbonic  anhydride 22.87  *. . . . 

Lime 6.53  6.53 

Potash 25.65  25.65 

Soda .21.62  21.62 


99.50  112.90 

Undetermined  and  loss .50    less  -fa     11.29 


loo.oo  101.61 

— (Scheibler.f) 

III.  Mixture  of  ash  from  a  refinery  laboratory  accumulated  in  one  year's  work, 
and  hence  probably  a  very  good  average. 

Potash   34.19 

Soda n.  12 

Lime 3.60 

Magnesia .16 

Ferric  oxide  and  alumina .28 

Sulphuric  anhydride 48.85 

Sand  and  silica 1.78 


99.98 
— (J.  W.  McDonald.t) 

RAW  CANE-SUGAR  ASH.      AVERAGE  COMPOSITION. 

I.             Carbonate  of  lime 49.00 

Carbonate  of  potassium 16. 50 

Sulphates  of  sodium  and  potassium 16.00 

Chloride  of  sodium 9.00 

Silica  and  alumina 9. 50 

100.00 
-(Monier.) 

*  Driven  off  by  sulphuric  acid.  f  Stammer's  Jahresbericht,  iv.  235. 

\  Chem.  Neivs,  xxxvii.  127. 


224  ANALYSIS  OF  KAW  SUGAR. 


II.  Demerara  sugar  containing  1.38  per  cent,  ash  of  the  following  composition  : 

Potash 29.10 

Soda ,,  1.94 

Lime 15.10 

Magnesia 3.76 

Sulphuric  anhydride  » . . . .  23.75 

Phosphoric  anhydride 5.59 

Carbonic  acid 4.06 

Chlorine 4.15 

Ferric  oxide 55 

Alumina : .65 

Silica 12.38 


101.03 
Deduct  oxygen  equivalent  to  chlorine .93 


100. 10 


The  juice  from  which  this  sugar  was  made  is  supposed  to  have  been 
treated  only  with  lime  (Wallace).* 

III.  Sulphated  ash  from  one  year's  work  in  a  refinery  laboratory  : 

Potash 28. 79 

Soda 87 

Lime ' 8.83 

Magnesia 2.73 

Ferric  oxide  and  alumina 6.90 

Sulphuric  anhydride 43-65 

Sand  and  silica 8.29 

100.06 
— (J.  W.  McDonald.f) 

The  estimation  of  the  ash  is  made  by  incinerating  from 
two  to  three  grammes  of  the  sugar  in  a  small  platinum  dish 
at  a  red  heat ;  the  difference  in  weight  of  the  dish  Before 
and  after  ignition  gives  the  absolute  quantity  of  ash,  which 
multiplied  by  100  and  divided  by  the  amount  of  the  assay 
gives  the  percentage. 

Soluble  Ash. — A  simple  incineration  of  the  sugar  gives 
the  total  ash,  regardless  of  its  composition.  As  insoluble 

*  Chem.  News,  xxxvii.  76.  f  Ibid.,  xxxvii.  127. 


ALKALINE  ASH.  225 

matters,  like  sand  and  clay,  do  not  exert  any  injurious  ac- 
tion on  the  sugar  in  the  process  of  refining,  it  is  often 
desirable  to  know  the  soluble  part  of  the  ash.  This  may 
be  determined  as  follows :  Weigh  from  two  to  five  grammes 
of  substance,  dissolve  in  a  little  boiling  water,  filter  hot, 
wash  with  hot  water,  and  evaporate  the  filtrate  and  wash- 
ings in  a  tared  platinum  dish ;  ignite  the  dry  residue,  burn 
oif  the  carbon,  and  weigh. 

Alkaline  Ash. — On  account  of  the  great  volatility  of 
the  alkaline  carbonates  which  form  a  large  portion  of 
sugar  ashes,  the  heating  for  a  sufficient  time  to  oxidize  the 
carbon  will  result  in  a  considerable  loss  by  volatilization, 
rendering  the  result  of  the  estimation  too  low.  It  is  well 
known  that  in  general  the  salts  of  the  alkali  metals  have  a 
powerful  melassigenic  effect  in  preventing  cane-sugar  from 
crystallizing,  and  in  inversion,  while  many  of  the  other  con- 
stituents of  sugar-ash  are  almost  inert  in  this  respect  (see 
page  64).  To  be  able  to  estimate  the  amount  of  alkaline 
salts  in  a  given  ash  is,  therefore,  a  desideratum.  This  result 
may  be  reached  in  the  following  way  :  Thoroughly  carbon- 
ize the  sugar ;  transfer  the  coal  to  a  small  mortar,  pulver- 
ize; wash  well  with  hot  distilled  water  and  filter;  evapo- 
rate the  filtrate  and  washings,  and  dry  the  residue  on  a 
water-bath;  or  determine  the  amount  of  alkaline  carbo- 
nates by  standard  acid  solution  in  the  ordinary  process  for 
alkalimetric  estimation  (page  258).  By  the  carbonization, 
the  salts  are  mostly  transformed  into  carbonates,  and  dur- 
ing the  lixiviation  the  comparatively  non-injurious  lime 
salts  remain  on  the  filter  in  great  part,  together  with  sand, 
clay,  alumina,  magnesium,  carbonate,  and  other  matters. 
Small  quantities  of  caustic  lime  and  other  bodies  are  dis- 
solved along  with  the  alkaline  carbonates,  owing  to  the  re- 


226  ANALYSIS  OF  RAW  SUGAR. 

duction  of  sulphates  to  sulphides,  but  by  far  the  greater 
portion  of  the  dissolved  salts  consist  of  sodium  and  potas- 
sium carbonates,  and  alkaline  chlorides. 

Sulphated  Ash.— Scheibler  *  has  proposed  the  incinera- 
tion of  sugars  with  the  addition  of  concentrated  sulphuric 
acid.  The  advantages  of  this  method  are  (1)  that  the  car- 
bonization in  the  presence  of  the  acid  furnishes  a  porous 
coal  which  burns  off  rapidly  and  without  much  swelling, 
while  in  the  ordinary  way  the  charred  mass  is  apt  to  be- 
come hard  and  graphitic  ;  (2)  that  the  bases  are  converted 
into  sulphates,  with  the  expulsion  of  chlorine  and  carbonic 
acid,  whereby  the  loss  by  volatilization  is  greatly  dimin- 
ished, as  the  sulphates  are  very  stable  at  a  red  heat  com- 
pared with  chlorides  or  carbonates.  The  ash  is  thus  deter- 
mined :  Two  to  three  grammes  of  sugar  are  weighed  in  a 
Fig.  31.  small  tared  platinum  dish,  as  shown 

in  Fig.  31,  45  mm.  in  diameter,  14 
mm.  high,  with  a  flat  or  convex  bot- 
tom ;  from  fifteen  to  thirty  drops  of 
pure  concentrated  sulphuric  acid 
are  added  to  the  sugar  in  the  dish,  and  the  heat  applied  at 
first  rather  gently,  and  then  to  full  redness.  Nothing  is 
gained  by  having  too  large  a  flame,  as  the  carbon  burns  off 
most  rapidly  with  a  moderate  red  heat.  Scheibler  has  pro- 
posed the  use  of  a  platinum  muffle,  which,  when  many  de- 
terminations are  to  be  made,  will  be  found  useful.  It  is 
figured  at  32.  The  dimensions  of  the  muffle  to  hold  three 
dishes,  as  described  above,  are  150  mm.  length,  55  mm. 
width,  and  25  to  30  mm.  high.  It  should  slightly  taper 
towards  one  end,  which  is  elevated  somewhat  so  as  to  al- 
low the  air  a  good  draught  through  the  apparatus.  When 

*  Stammer's  Jahresb.,  iv.  221 ;  vii.  267. 


SULPHATED  ASH. 


227 


the  carbon  is  completely  burned  off,  the  dish  is  allowed  to 
cool  and  reweighed.  If  the  amount  of  ash  is  large,  or  it  is 
very  fusible,  it  will  often  happen  that  the  last  portions  of 
carbon  are  oxidized  with  difficulty.  In  such  a  case  the 
dish  is  allowed  to  cool,  one  or  two  drops  of  sulphuric  acid 
added,  and  the  dish  heated  cautiously  at  first  to  avoid 
spattering,  and  finally  brought  to  redness  for  fifteen 
minutes. 
As  the  equivalent  of  sulphuric  acid  is  greater  than 

Fig.  32. 


that  of  carbonic  acid  (in  proportion  of  40  :  22),  it  is 
necessary  to  reduce  the  net  weight  of  the  sulphated  ash  to 
the  figure  that  represents  the  carbonated  ash.  Scheibler 
has  found  that  a  subtraction  of  one-tenth  from  the*  weight 
of.  the  sulphated  ash  will  do  this  approximately.  Though 
the  discrepancy  mentioned  above  is  not  constant  for  all 
sugars,  yet  the  results  given  by  the  method  are  near  enough 
to  the  truth  for  all  practical  purposes.*  Example : 

Sugar  plus  dish 12.121 

Dish 10.110 

Sugar  taken 2.011 

*  Violette  (Amer.  Chemist,  v.  296)  considers  that  the  coefficient  f0-  should  be 
used  in  general,  and  -&-  for  very  pure  raw  sugars. 


228 


ANALYSIS  OF  RAW  SUGAR. 


Dish  plus  ash..  10.120 

Dish  ...........  10.110 

—     .009X100 
Ash  ............  010      ~ 


=  '44 


cent' 


Less 


001 


.009 

The  process  with  sulphuric  acid  is  preferable  to  the  sim- 
ple incineration  for  accuracy,  general  agreement  of  results, 
and  facility  of  execution.  The  soluble  ash  can  also  be 
made  by  the  sulphuric-acid  method.  It  is  to  be  recom- 
mended that  with  sugars  containing  much  sand,  clay,  and 
other  insoluble  impurities,  the  soluble  ash  be  taken,  as  this 
represents  the  amount  of  the  salts  which  go  into  solution 
in  the  operation  of  refining. 


SCHEME    FOR  THE  EXAMINATION   OF  SUGAR-ASH. 

Dissolve  10  grammes  of  the  sugar  in  water,  dilute  to  100 
c.c.,  and  filter : 


A.  Dry  filter ;  ignite 
in  tared  platinum  dish  ; 
subtract  filter  ash. 

Residue  = 

Sand,  Clay,  etc. 


B.  Evaporate  25  c.c. 
(—2-5  grammes  sugar) 
of  the  filtrate  in  a  tared 
dish,  add  sulphuric 
acid,  carbonize,  burn  off 
coal,  and  weigh;  sub- 
tract -jV  from  residue. 

=  Soluble  Ash. 


C.  50  c.c.  (  =  5  grms. 
sugar)    of    filtrate     are 
evaporated    in   a   plati- 
num  dish,    carbonized, 
the   coal   washed     with 
hot  distilled  water,  and 
the  washings,  after  fil- 
tration,   evaporated   on 
water-bath  to  dryness. 

Result  = 
Alkaline  Ash.* 

D.  The  alkaline  ash 
is  titred  with  standard 
acid. 

Result  = 

Alkaline  Carbo- 
nates. 


*  Alkaline  chlorides  and  carbonates. 


COLORIMETRY.  339 

The  relation  between  the  sulphated  ash  and  the  salts  as 
they  exist  in  the  raw  sugar  is  such,  according  to  Landolt, 
that  one  part  of  the  former  is  equivalent  to  two  parts  of 
the  latter.  This  is  for  beet-sugars. 

ESTIMATION  OF  THE  COLOR. 

Several  instruments  have  been  invented  for  effecting  a 
comparison  of  color  between  sugar  solutions.  Of  these 
Pay  en's  decolorimeter  and  its  modification,  Ventzke's,  have 
for  their  object  the  estimating  of  the  decolorizing  power  of 
char.  Salleron's,  Duboscq's,  and  Stammer's  colorimeters, 
and  Stammer's  chromoscope,  are  more  general  in  their  ap- 
plication, and  permit  the  color-comparison  of  all  saccharine 
products,  solid  and  liquid,  as  well  as  the  estimation  of  the 
decolorizing  power  of  animal  black.  None  of  these  appli- 
ances, with  the  exception  of  Stammer's  colorimeter  (Far- 
benmdss),  have  a  standard  of  comparison  in  the  instrument 
itself ;  the  results  are  merely  comparisons  with  standard 
solutions  of  caramel,  which  in  practice  are  found  to  be 
exceedingly  difficult  to  make  twice  alike  by  the  same 
operator.  Hence  estimations  made  with  such  standards 
have  necessarily  a  considerable  element  of  uncertainty  in 
them. 

Stammer's  Colorimeter  (not  to  be  confounded  with 
his  chromoscope)  approaches  nearest  to  an  absolute  stan- 
dard, the  results  obtained  by  different  instruments  and 
operators  by  Stammer's  process  being  generally  strictly 
comparable.  The  apparatus  is  shown  in  Fig.  33.  The 
solution-tube  I  is  closed  at  its  lower  extremity  by  a  glass 
plate,  and  is  open  above,  where  it  is  provided  with  a  lip 
by  which  the  sugar  solutions  may  be  poured.  I  is  fixed 


230 


ANALYSIS  OF  RAW  SUGAR. 


to  the  wooden  support  by    two    screws,  which,  when  it 
is  necessary  to  clean  the  instrument,    can    be  easily  re- 


Fig-    33- 


moved.  The  measuring  - 
tube  III  is  closed  below 
by  a  glass  plate,  and  moves 
freely  up  and  down  in  the 
solution-tube  I.  II,  fas- 
tened to  III,  is  open  be- 
low, and  at  its  upper  ex- 
tremity is  covered  by  the 
colored  glasses  which  form 
the  standard  of  compari- 
son ;  at  the  lower  portion 
of  it  are  two  rings  with 
screws,  which  are  connect- 
ed 'with  a  slide  moving  in 
a  groove  cut  in  the  wooden 
support  shown  in  the  fig- 
ure. The  slide  serves  as 
an  indicator  of  a  milli- 
metre scale  placed  at  the 
back  of  the  wooden  frame, 
for  the  purpose  of  measur- 
ing the  perpendicular  dis- 
tance that  the  joined  tubes, 
II  and  III,  may  be  raised. 
The  standard  consists 
of  two  glasses,  and  a  de- 
gree of  color  equal  to  them 
is  called  100.  Besides  this, 
the  apparatus  is  provided  with  two  separate  colored  glasses, 
each  equal  to  one  of  the  plates  forming  the  standard,  and 


COLORIMETRY.  231 

may  be  employed  in  the  place  of  the  standard,  being  equi- 
valent to  one-half  of  it  in  color  intensity  ;  also  one  or  both 
may  be  used  with  the  standard  glasses,  when  the  combina- 
tions are  equal  respectively  to  one  and  a  half  times,  and 
double  the  normal  standard.  The  eye-piece  V  consists  of 
an  optical  arrangement  whereby  the  color  due  to  the  so- 
lution under  examination,  and  that  from  the  colored 
glasses,  are  made  to  appear  on  either  side  of  a  vertical 
line  dividing  a  circular  disk,  making  a  luminous  field 
similar  to  that  of  the  Soleil  saccharimeter.  In  this  man- 
ner an  accurate  comparison  of  color  may  be  obtained. 
The  eye-piece  can  be  fitted  on  the  top  of  the  tubes  II 
and  III  after  the  standard  glasses  are  placed  in  position  in 
the  upper  part  of  II.  A  mirror  at  the  bottom  reflects  the 
light  upward  through  the  tubes,  and  a  screw  behind  the 
wooden  frame  attached  to  the  tube  II  enables  the  operator 
to  elevate  or  depress  at  will  II  and  III.  The  whole  appa- 
ratus is  mounted  on  a  wooden  stand,  as  shown  in  the  cut. 
The  manner  of  using  is  as  follows :  The  operator  fills  the 
solution-tube  to  the  proper  height  with  the  liquid  to  be  ex- 
amined, and  then,  looking  through  the  ocular,  by  means  of 
the  large  screw  attached  to  the  frame  elevates  gradually 
the  tubes  II  and  III,  until  after  repeated  trials  the  two 
halves  of  the  luminous  disk  appear  of  the  same  intensity 
of  color.  At  this  point  the  screw  is  turned  so  as  it  keeps 
the  apparatus  in  the  position  thus  obtained,  and  the  read- 
ing of  the  scale  taken,  which  shows  the  amount  of  perpen- 
dicular elevation.  The  more  III  has  been  raised,  the 
greater  the  depth  of  the  column  of  liquid  between  the  bot- 
toms of  I  and  III.  The  color-intensity  of  this  column  is 
compared  with  standard  glasses.  A  solution  before  use 
must  be  rendered  perfectly  clear,  by  filtration  if  necessary. 


232  ANALYSIS  OF  RAW  SUGAR. 

The  color  of  a  solution  is  in  inverse  ratio  to  the  length  of 
a  column  of  it  necessary  to  produce  a  given  color.  If  the 
comparative  color  be  expressed  by  100,  it  follows  that  the 
readings  in  millimetres  must  be  divided  into  100  to  get  the 
figure  expressing  the  relative  color. 

The  apparatus  may  be  cleaned  by  loosening  the  screws 
holding  the  rings  on  the  bottom  of  II,  when  the  latter  can 
be  raised  out  of  the  solution  together  with  the  tube  III. 

Calculation. — The  estimation  of  the  color  of  raw  sugar, 
Fullmass,  or  other  material  can  be  calculated  on  one  hun- 
dred parts  of  cane-sugar  contained,  and  the  result  shows 
the  relation  of  color  to  the  saccharimetric  strength.  A  so- 
lution of  the  substance  to  be  estimated  is  made  by  dissolv- 
ing a  known  weight  in  water  and  making  the  solution  up 
to  100  c.c.  It  is  convenient  to  take  the  normal  solution  in- 
tended for  the  polariscope.  The  clear  solution  is  placed  in 
the  colorimeter  and  the  reading  taken,  which  is  divided 
into  100.  If  the  solution  is  too  dark  for  use  with  the 
standard,  one  or  both  of  the  extra  colored  plates  may  be 
put  in  and  the  readings  (before  division  into  100)  divided 
by  \\  or  2 ;  cr  the  dark  solution  may  be  diluted  to  twice, 
four  times,  or  any  desired  volume,  the  reading  being  di- 
vided by  2,  4,  etc.,  to  reduce  to  the  standard  of  the  colori- 
meter. If,  on  the  other  hand,  the  solution  is  too  light,  the 
standard  glass  may  be  replaced  by  one  of  the  extra  glasses 
and  the  reading  multiplied  by  two.  These  directions  ap- 
ply to  the  use  of  the  colorimeter,  whether  for  solids  or 
liquids.  Example  :  15  grammes  of  a  raw  sugar  polarizing 
85  were  dissolved  in  water  and  the  solution  filtered,  after 
making  up  to  100  c.c.  On  trial  with  the  colorimeter  it  was 
found  to  be  too  dark,  and  the  two  extra  glasses  were  put  in, 
when  the  reading  was  36.  The  calculation  would  then  be 


COLORIMETRY.  233 


O/>  -t  s\s\ 

as  follows  :   -^-  =  18  =  -jg-  =  5.55,  which  is  the  number 

15  X  85 
expressing  the    color  '  corresponding  to  —      —  =   12.75 


grammes  cane-sugar  in  100  c.c.    of    solution.      Now,   as 
12.75  :  5.55  =  100  :  #,  x  =  43.5  ;   which  is  the   color   corre- 
sponding to  one  hundred  parts  of  cane-sugar. 
Monier's*    Method    with   Standard    Colors.  —  For 

those  not  having  a  colorimeter  this  process  may  be  found 
useful,  though  in  every  way  less  satisfactory  than  the  pre- 
ceding. A  series  of  ten  standard  colors  are  prepared  by 
dissolving  known  weights  of  caramel  in  a  fixed  volume  of 
water,  say  25  c.c.,  in  arithmetical  progression,  the  first 
tube  containing  one  part  caramel,  the  second  two  parts,  the 
third  three  parts,  and  so  on.  In  order  to  make  a  compari- 
son of  raw  sugar  by  this  method  five  grammes  are  weighed, 
dissolved  in  water,  and  the  solution  made  up  to  the  bulk  of 
the  standard  solutions,  after  filtration.  A  comparison  is 
now  made  between  the  raw  sugar  solution  and  the  stan- 
dards, the  one  it  most  nearly  approaches  in  color  being  that 
which  contains  the  same  amount  of  coloring  matter  as  the 
raw  sugar.  For  preparation  of  the  caramel  see  page  331. 

ESTIMATION   OF  THE  ORGANIC   MATTER  NOT   SUGAR. 

In  commercial  analysis  these  bodies  are  determined  by 
difference,  the  sum  of  the  sugar,  grape-sugar,  water,  and 
ash  being  subtracted  from  one  hundred,  and  the  remainder 
called  the  organic  or  undetermined  matters.  Included  in 
the  above  term  is  a  great  variety  of  substances,  nitroge- 
nous and  non-nitrogenous,  of  which  the  chief  are  organic 

*  Guide  pour  Vessai  et  V  analyse  des  sucres.    Paris. 


234  ANALYSIS  OF  RAW  SUGAR. 

acids  combined  with  bases  found  in  the  ash,  gum,  coloring 
matter,  albuminous  bodies,  and  insoluble  organic  matters, 
as  particles  of  cane  or  beet,  and  cellulose.  Some  of  these 
bodies  are  inert  in  their  action  on  cane-sugar  in  the  process 
of  the  manufacture  or  refining  of  sugar,  while  others  are 
very  injurious,  such  as  the  gummy  matters,  in  hindering  or 
preventing  crystallization,  arid  the  protein  compounds, 
which  tend  to  set  up  fermentation  of  various  orders  in 
sugar  liquids.  Though  for  most  commercial  purposes  the 
estimation  by  difference  is  sufficient  when  all  the  other  de- 
terminations are  made  correctly,  yet  in  some  cases  it  is 
desirable  to  estimate  directly  the  organic  substances,  and  to 
discriminate,  if  possible,  between  them  in  regard  to  their 
greater  or  less  injurious  action  on  sugar  solutions.  The 
method  by  difference  is  open  to  the  objection  that  all  the 
errors  of  the  other  determinations  fall  upon  the  undeter- 
mined matters  and  make  it  too  high  or  too  low,  as  the  case 
may  be.  This  fact  greatly  lowers  the  value  of  the  figures 
representing  the  organic  substances  in  many  commercial 
analyses. 

WalkoflPs  Method.— This  is  based  on  the  fact  that 
tannin  precipitates  from  raw  sugar  solutions  most  of  the 
nitrogenous  matters  and  some  other  bodies.  Two  grammes 
of  pure  dry  tannin  are  dissolved  in  distilled  water,  and 
the  volume  made  up  to  one  litre;  1  c.c.  of  this  solution 
contains  .002  gramme  tannin.  About  five  grammes  of  the 
sugar  to  be  tested  are  dissolved  in  200  c.c.  of  water,  the  so- 
lution heated  moderately,  and  the  tannin  added  from  a 
burette.  A  flocculent  precipitate  forms,  which  gradually 
settles.  From  time  to  time  a  small  portion  of  the  liquid  is 
taken  out,  filtered  after  the  manner  described  under  Esti- 
mation of  Grape-Sugar,  page  197  in  connection  with  Fehl- 


t 

ESTIMATION  OF  ORGANIC  MATTER. 


ing's  solution,  and  a  drop  of  a  solution  of  ferrous  sulphate 
is  added  to  the  filtrate.  As  soon  as  a  dark  color  is  pro- 
duced in  contact  with  the  iron  salt  the  tannin  is  in  excess, 
and  the  end  point  of  the  reaction  is  attained.  The  weight 
of  tannin  employed,  calculated  from  the  number  of  cubic 
centimetres  used,  divided  by  six,  represenst  the  amount  of 
organic  matters  precipitated.  The  sugar  solution  should 
be  perfectly  neutral.  The  relation  between  the  tannin  and 
the  organic  matters  precipitated  by  it,  given  above,  was  ob- 
tained for  beet  products,  and  it  is  probable  that  for  those 
of  the  cane  the  proportion  is  different.  When  the  process 
is  used  for  the  latter,  the  relation  might  be  determined  by 
precipitating  an  impure  sugar  solution  with  a  known  quan- 
tity of  tannin  insufficient  to  completely  throw  down  the 
matters  in  solution,  collecting  on  a  weighed  filter,  drying 
at  100°,  and  calculating  the  amount  of  tannin  correspond- 
ing to  the  other  substances. 

WalkofFs  process,  though  somewhat  empirical,  is  capa- 
ble of  giving  good  comparative  results.* 

Subacetate  of  Lead  Method. — The  basic  acetate  of 
lead,  it  is  well  known,  precipitates  a  large  portion  of  the 
organic  substances  present  in  raw  sugars.  Besides  the 
nitrogenous  bodies  precipitable  by  tannin,  gummy  and 
coloring  matters,  and  many  organic  acids,  are  carried  down. 
Twenty  grammes  or  more  of  the  sugar  are  dissolved  in  a 
moderate  quantity  of  warm  water,  and  an  excess  of  solu- 
tion of  lead  subacetate  added ;  after  heating  a  few 
minutes  the  solution  is  filtered,  the  precipitate  thoroughly 
washed,  diffused  in  water  together  with  any  portions  of 

*  Pellet  and  Pelton,  as  the  result  of  an  exhaustive  examination  of  the  ac- 
tion of  tannic  acid  on  beet-molasses,  consider  WalkofFs  process  unreliable,  as 
asparagine  is  not  precipitated. 


236  ANALYSIS  OF  RAW  SUGAR. 

the  filter  from  which  it  is  difficult  to  detach  the  precipitate, 
and  treated  with  gaseous  sulphuretted  hydrogen  until  the 
lead  is  all  thrown  down  as  sulphide,  leaving  the  organic 
substances  that  were  combined  with  the  oxide  of  lead  in 
solution.  The  precipitated  plumbic  sulphide  is  filtered 
from  the  solution,  washed,  and  the  combined  washings 
and  filtrate  evaporated  to  dryness  in  a  tared  dish  on  a 
water-bath,  the  heating  being  continued  till  the  mass  ceases 
to  lose  weight.  This  method,  though  somewhat  tedious  to 
execute,  may  furnish  results  of  comparative  value. 

Schrotter  and  Monier  have  proposed  a  volumetric  method 
with  permanganate  of  potassium,  but  it  is  of  very  doubtful 
advantage.  For  the  separate  estimation  of  the  organic 
matters  in  raw  sugar  products  see  Laugier,  Guide  pour 
V  analyse  des  matter  es  sucrees* 

ESTIMATION   OF  INSOLUBLE  MATTER. 

These  substances  include  particles  of  cane  or  beet  fibre, 
accidental  organic  or  inorganic  impurity,  sand,  clay,  etc. 
20  to  50  grammes  of  the  sugar  are  taken,  dissolved  in  boiling 
water  to  make  a  rather  dilute  solution,  which  is  filtered 
through  a  tared  filter,  by  the  aid  of  a  vacuum-pump  if  ne- 
cessary. After  washing  sufficiently,  the  filter  is  dried  at 
100°  C.  until  it  ceases  to  lose  weight,  and  the  final  weight, 
after  the  subtraction  of  that  of  the  filter,  gives  the  amount 
of  'insoluble  impurities.  To  find  the  proportion  of  the  or- 
ganic and  inorganic  constituents,  the  filter  is  burned  to  an 
ash  in  a  weighed  crucible ;  after  the  subtraction  of  the 
weight  of  crucible  and  filter  ash,  the  remainder  is  the  inor- 

*  Zeit.  f.  Riibenz ,   xxviii.  805;  Stammer's  Jahresb.,   xviii.  222;  Bittman, 
Stammer's  Jahresb.,  xix.  240. 


ESTIMATION  OF  YIELD.  237 

ganic  insoluble  impurities  (sand,  clay,  etc.)  The  diffe- 
rence between  the  latter  and  the  total  constitutes  the 
organic  insoluble  impurities. 

ESTIMATION   OP  THE  YIELD. 

It  is  important  to  be  able  to  estimate  the  amount  of  cane- 
sugar  obtainable  in  refining  from  a  given  sample  of  raw  su- 
gar. The  buyer  or  seller  who  has  no  knowledge  of  chemis- 
try finds  it  very  convenient  to  make  use  of  a  single  figure 
summing  up  the  results  of  the  chemical  analysis  which, 
perhaps,  he  is  able  to  but  imperfectly  interpret.  It  has 
long  ago  been  observed  that  two  raw  sugars  having  the 
same  polarization  give  quite  different  results  in  refining,  as 
to  yield  in  crystallizable  sugar ;  and  this  is  rightly  attri- 
buted to  the  varying  nature  and  quantity  of  the  impurities, 
which  either  tend  to  destroy  the  cane-sugar  by  inversion  or 
to  prevent  its  crystallization. 

Method  of  Coefficients. — It  is  also  a  well-recognized 
fact  that  saline  matters  have  a  particularly  injurious  effect 
on  the  cane-sugar  in  refining,  and  that  in  the  syrups  from 
which  no  longer  any  sugar  can  be  crystallized,  there  is  a 
more  or  less  fixed  relation  between  the  salts  and  the  un- 
crystallizable  cane-sugar.  These  considerations  gave  rise 
to  the  method  of  valuing  raw  sugars  that  is  in  extensive 
use  in  France,  and,  somewhat  modified,  is  adopted  in  the 
French  government  laboratories  for  sugar  analysis.  This 
method  assumes  that  for  every  part  of  ash  in  the  raw  sugar 
five  parts  of  cane-sugar  are  prevented  from  crystallizing, 
and  that  for  each  part  of  glucose  or  grape-sugar  one  or  two 
parts  (according  to  commercial  convention)  are  carried  per- 
manently into  the  molasses.  Thus,  a  sugar  containing 


238  ANALYSIS  OF  RAW  SUGAR. 

Sugar 92.00 

Glucose 2.00 

Ash 1.00 

by  the  method  of  the  coefficients  would  give 

(1  X  5)  +  (2.00  X  1)  =  7,  or  (1x5)  +  (2.00  X  2)  =  9,' 

which,  subtracted  from  the  amount  of  cane-sugar,  shows  a 
yield  of  85  or  83.  The  above  is  the  method  in  the  form 
most  used,  though  many  have  considered  the  coefficient  5 
too  high,  and  figures  varying  from  3.5  to  5  have  been  pro- 
posed, and  to  a  certain  extent  adopted.  In  raw  beet-sugars 
containing  very  small  quantities  of  grape-sugar  the  glucose 
factor  is  neglected. 

A  commission  appointed  by  the  French  government, 
composed  of  MM.  Aime  Girard,  De  Luynes,  and  other 
chemists,  have  recommended  this  mode  of  valuing  raw  su- 
gars, which  has  been  adopted,  and  is  now  the  officially 
recognized  method.  The  scheme  submitted  by  the  above 
chemists  is  as  follows :  From  the  percentage  of  cane-sugar 
given  by  the  saccharimeter  is  subtracted  the  sum  of— 

(1)  Four  times  the  weight  of  the  ash  (ash  burned  with 
addition  of  sulphuric  acid,  and  one-fifth  subtracted) ; 

(2)  Twice  the  glucose  when  the  titre  is  1  per  cent,  or 
above ;  the  glucose  multiplied  by  1  when  the  titre  is  be- 
tween 1  per  cent,  and  f  per  cent.  ;  when  the  titre  is  below 
J  per  cent,  the  glucose  is  neglected  ; 

(3)  1£  per  cent,  for  waste  in  refining. 

Thus  the  sugar  whose  analysis  was  given  above  would 
show  a  yield  of 

(1  X  4)  +  (2.00  X  2)  + 1.50  =  9.50  ;  92.00  -  9.5  =  82.5. 
The  method  of  coefficients  described,  and  used  in  France 


THE  SALINE  COEFFICIENT.  239 

for  the  commercial  valuation  of  raw  sugars,  though,  doubt- 
less justified  for  certain  beet  and  high-grade  cane  sugars,  is 
open  to  serious  objection.  The  results  given  by  it  necessa- 
rily vary  a  great  deal,  approaching  near  the  truth  for  some, 
but  falling  far  short  for  others,  being  generally  too  low. 
On  this  account  the  system  has  never  obtained  outside  of 
France.  The  various  saline  impurities  have  individually 
very  unequal  injurious  effect  on  cane-sugar,  some  being 
almost  inert  and  others  very  hurtful ;  besides  which  the 
organic  impurities  have  also  an  injurious  action.  The 
soluble  portion  of  the  ash,  the  only  one  that  can  have  any 
melassigenic  action,  in  raw  cane-sugars  is  frequently  not 
more  than  one-half  to  three-fourths  of  the  total,  while  with 
raw  beet-sugars  nearly  the  whole  is  soluble,  and  consists 
largely  of  the  most  melassigenic  salts — namely,  those  of 
potassium.  Further,  the  ash  in  all  raw  sugars  varies  with 
many  circumstances — the  methods  of  manufacture,  the 
spil,  manure,  etc. — and  to  lay  down  a  hard-and-fast  rule 
to  measure  its  injurious  action  is  not  only  empirical,  but, 
from  the  nature  of  the  case,  must  be  very  unreliable.  The 
error  of  the  method  in  giving  results  that  are  too  low  is 
much  more  apparent  with  raw  cane,  than  with  raw  beet  su- 
gars. Take,  for  example,  a  number  of  type  analyses  of 
Cuba  sugars ; 


340 


ANALYSIS  OF  RAW  SUGAR. 


Good  cen- 

Fair cen- 

Good mus- 

Fair mus- 

Molasses- 

trifugal. 

trifugal. 

covado. 

covado. 

sugar. 

Sufirar.  . 

6 

QO.OO 

86.OO 

81.50 

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2.  IO 

O_  QQ 

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6.  50 

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en 

It  will  be  readily  seen  by  those  who  are  experienced  in 
these  matters  that  the  above  yields  for  the  higher  grades, 
more  closely  approximate  the  actual  refining  results,  while 
for  the  lower  grades  the  calculated  yield  falls  much  short 
of  the  actual. 

PAYEE'S  PROCESS,  MODIFIED  BY  SCHEIBLER. 
(RqffinationwertJis — Rendements.) 

Raw  sugar,  washed  with  alcohol  of  about  eighty -five 
per  cent,  saturated  with  cane-sugar,  is  deprived  of  its 
syrup.  This  consists  in  part  of  glucose,  and  partly  of  cane- 
sugar  that  has  lost  the  ability  to  crystallize  owing  to  the 
presence  of  various  foreign  bodies,  together  with  most  of 


PAYEN'S  METHOD.  241 

the  other  impurities,  as  coloring  matters,  salts,  etc.  The 
residue  from  this  operation  is  the  cane-sugar  actually  crys- 
tallized in  the  raw  product,  plus  tJie  cane-sugar  held  dis- 
solved in  the  water  present,  and  precipitable  by  the  wash- 
ing solutions. 

Pay  en's  original  method  is  executed  in  the  following 
way :  The  wash-liquor  is  made  by  saturating  one  litre  of 
88  per  cent,  alcohol  to  which  50  c.c.  of  strong  acetic  acid 
is  added,  with  finely-pulverized  cane-sugar.  The  object  of 
the  acid  is  to  decompose  sucrates  and  render  the  saline 
matters  more  soluble.  Ten  grammes  of  the  sugar  to  be  ex- 
amined is  first  treated  with  absolute  alcohol  to  deprive  it 
of  water,  and  then  with  50  c.c.  of  the  alcoholic  sugar  solu- 
tion, the  assay  being  placed  in  a  small  tube  the  solu- 
tions poured  upon  it  and  allowed  to  filter  through.  A 
second  and  third  washing  is  given  if  necessary,  the  last 
wash-liquor  consisting  of  96  per  cent,  alcohol  saturated 
with  sugar.  The  purified  material  is  then  brought  on  a 
tared  filter,  dried  at  100°,  and  weighed. 

The  method  remained  in  this  form  for  many  years  and 
was  but  little  used.  In  1871  Dr.  Scheibler,  of  Berlin,  in 
competition  for  a  prize  offered  by  the  Society  of  the  Beet- 
Sugar  Industry  of  the  Zollverein,  revived  the  process  of 
Payen,  and  so  improved  the  manner  of  executing  it  as  to 
make  it  a  practically  useful  method. 

It  cannot  be  properly  claimed  that  Pay  en's  method  gives 
the  absolute  yield  that  raw  sugars  will  show  in  refining, 
for  that  depends  not  only  upon  the  manner  of  working, 
whereby  greater  or  less  perfection  is  attained,  but  also 
upon  the  fact  that  the  organic  or  inorganic  impurities  may 
differ  in  amount  or  kind  independently  of  the  percentage 
of  crystallizable  sugar  present.  For  example,  two  raw 


242  ANALYSIS  OF  RAW  SUGAR. 

sugars  giving  a  yield  by  this  process  of  90,  the  one  con- 
taining one  per  cent,  of  total  impurities  of  a  slightly  melas- 
sigenic  nature,  and  the  other  three  per  cent,  of  a  more  in- 
jurious character :  it  is  evident  that  the  amount  of  sugar 
obtainable  in  refining  will  be  very  different  from  the  two 
sugars.  As  a  relative  standard,  however,  the  method, 
when  properly  executed,  is  capable  of  giving  valuable  in- 
formation in  regard  to  the  worth  of  raw  sugars,  as,  cceteris 
paribus,  the  more  crystallizable  sugar  present  the  greater 
the  yield.  The  only  legitimate  interpretation  of  the  results 
by  Pay  en's  method  is  to  consider  the  latter  as  an  analytical 
process  for  determining  the  total  cane-sugar  present,  ex- 
clusive of  that  permanently  in  the  form  of  syrup. 

The  following  is  a  description  of  the  manner  of  making 
the  estimation  with  the  improvements  of  Scheibler  and 
others.*  There  are  four  liquids  used,  viz. : 

Wo.  1,  consisting  of  85  per  cent,  alcohol  to  which  50  c.c.  of 
acetic  acid  is  added  to  the  litre,  and  the  mixture 
allowed  to  stand  in  contact  with  a  large  excess  of 
powdered  sugar  for  a  day,  being  shaken  at  inter- 
vals. 

No.  2.  Alcohol  of  92  per  cent,  saturated,  as  above,  with 
sugar. 

No.  3.  Alcohol  of  96  per  cent.,  also  saturated  with  sugar. 

No.  4.  A  mixture  of  two-thirds  absolute  alcohol  and  one- 
third  ether. 

The  solutions  1,  2,  and  3,  after  saturation,  are  preserved 

*  Stammer's  JaJires'b.  :  Scheibler,  xii.  179,  195,  211;  xiii.  144,  148;  xiv. 
139;  Kohlrausch,  xii.  203;  xiii.  152;  Bodenbender,  xii.  196,  207;  Lotman,  xiv. 
145.  American  Chemist,  iii.  330;  iv.  85. 


PA  YEN'S  METHOD. 


243 


in  the  two-necked  bottles 
shown  in  Fig.  34,  provided 
with  a  syphon  delivery-tube, 
c,  for  drawing  off  the  solu- 
tion. The  bottles  are  loosely 
filled  with  lumps  of  pure 
white  sugar,  as  is  also  the  sy- 
phon ;  b  is  a  chloride  of  cal- 
cium tube  to  prevent  moist 
air  from  entering.  The  solu- 
tions may  be  saturated  with 
sugar  by  allowing  them  to 
stand  in  contact  with  a  large 
excess  of  the  pulverized  sub- 
stance, and  agitating  at  inter- 
vals until  the  operation  is 
complete.  The  bottle  for 
holding  ~No.  4  is  similar  to 
the  above,  the  syphon  being 
of  much  smaller  calibre.  The  washing-liquids  should  be 
placed  conveniently  for  use  in  a  situation  as  little  liable  to 
changes  of  temperature  as  possible. 

The  washing  of.  the  raw  sugar  takes  place  in  the  appara- 
tus figured  at  35,  one-fourth  of  the  natural  size.  A  is  a 
flask  graduated  to  50  c.c.,  which  is  closed  by  a  rubber 
stopper  of  two  perforations,  one  carrying  the  tube  n,. 
through  which  the  wash-liquids  are  added,  and  another,  0, 
which  reaches  nearly  to  the  bottom  of  the  vessel,  and  is 
enlarged  at  its  lower  extremity,  as  shown  in  the  cut.  This 
enlargement  serves  to  hold  the  filtering  material,  which 
consists  of  little  cylinders  of  the  felt  used  by  pianoforte 
manufacturers,  and  which  fits  tightly  in  the  tubes.  B  is  a 


244  ANALYSIS  OF  RAW  SUGAR. 

flask  which  acts  as  a  reservoir  for  the  solutions  after  they 
have  been  in  contact  with  the  raw  sugar  in  A,  and  from 
which  they  are  drawn  off  through  a  rubber  tube  connect- 
ing with  the  flasks,  by  a  suction  applied  to  B  by  a  small 
tube  as  shown.  An  ordinary  Bunsen  water- air  pump,  or 
any  other  arrangement  capable  of  providing  a  moderate 
exhaust,  is  suitable  for  the  purpose. 

Fig-  35- 


Execution  of  the  Test.— The  sample  of  raw  sugar  to 
be  tested  should  be  ground  in  a  mortar,  if  necessary,  to 
break  up  all  small  lumps.  The  half  normal  quantity  of 
the  Ventzke-Scheibler  saccharimeter  *  is  weighed  (13.024 
grammes)  and  transferred  to  A.  In  the  case  of  very  moist 
sugars  that  would  stick  to  the  weighing-dish,  it  would  be 
better  to  weigh  directly  into  A,  previously  tared.  The  first 
step  of  the  washing  is  to  run  from  No.  4  a  volume  of 
liquid  equal  to  twice  that  of  the  sugar,  and  allow  it  to  stand 

*  Or  any  other  quantity  to  suit  the  saccharimeter  used. 


PAYEN'S  METHOD.  245 

for  ten  minutes,  with  frequent  agitation  to  thoroughly  dis- 
integrate the  mass  of  sugar  and  to  allow  the  alcoholic  mix- 
ture to  do  its  work  well.  The  object  of  this  operation  is  to 
remove  the  water  and  at  the  same  time  to  precipitate  any 
cane-sugar  dissolved  in  it.  If  the  acid  solution  (No.  1) 
were  allowed  to  act  directly  on  the  moist  sugar,  it  would  be 
so  diluted  by  the  water  present  as  to  be  capable  of  dissolv- 
ing cane-sugar,  and  hence  make  the  result  too  low.  If  the 
sugar  contains  over  four  per  cent,  moisture,  it  is  advisable 
to  partially  dry  the  samples  after  weighing.  When  the 
alcohol  and  ether  have  remained  long  enough,  the  tube  r  is 
connected  with  0,  and  by  means  of  the  air-pump  the  liquid 
is  drawn  into  B  ;  then  solutions  2  and  3  are  added  succes- 
sively to  A,  shaken  up  with  the  sugar,  and  similarly  with- 
drawn. The  object  of  the  last  two  solutions  is  to  take  up 
the  last  traces  of  alcohol  and  ether.  Solution  No.  1  is  now 
run  into  A  in  quantity  equal  to  twice  the  bulk  of  the  sugar, 
and  allowed  to  stand,  with  frequent  shaking,  Jfor  ten  or  fif- 
teen minutes.  After  this  has  been  drawn  off,  a  second  and 
third  portion,  if  necessary,  is  used,  until  the  solution 
ceases  to  take  up  anything  more,  and  the  sugar  under 
treatment  has  reached  its  maximum  purity  and  whiteness. 
The  washing  with  No.  1  solution  is  the  most  important  in 
the  process,  and  the  time  of  washing  and  volume  of  wash- 
liquor  employed  must  be  left  to  the  judgment  of  the  ope- 
rator, as  they  vary  a  great  deal  for  different  kinds  of 
sugars.  After  the  last  portion  of  No.  1  has  been  carried 
off,  successive  quantities  of  Nos.  2,  3,  and  4  are  syphoned 
into  A  in  the  order  named,  and,  after  being  shaken  a  few 
moments  with  the  contents  of  the  flask,  removed.  Finally 
the  flask  A  is  gently  heated  while  the  pump  is  still  in  ope- 
ration, to  facilitate  the  removal  of  the  last  traces  of  alco- 


246  ANALYSIS  OF  RAW  SUGAR. 

hol  and  ether.  When  the  washings  are  finished  the  flasks 
are  disconnected,  the  filtering-tube  o  (Fig.  35)  taken  out, 
carefully  washed  from  any  adhering  particles  of  sugar  into 
the  flask  by  a  wash-bottle,  sufficient  water  added  to  dis- 
solve the  sugar  together  with  a  drop  or  two  of  lead  solu- 
tion, and  the  contents  of  the  flask  finally  made  up  to 
50  c.c.,  filtered,  and  polarized.  The  direct  reading  of 
the  saccharimeter  gives  the  percentage  of  crystallizable 
sugar. 

The  method  of  Payen-Scheibler,  though  apparently 
complicated,  is  in  reality  quite  simple  and  easy  of  execu- 
tion. Considerable  care  and  some  experience  with  it  are, 
however,  required  to  get  good  and  unvarying  results.  The 
chief  difficulty  with  the  method — one  which  is  especially 
prominent  in  a  climate  subject  to  such  sudden  changes  as 
that  of  the  United  States — is  that  the  solutions  which  at 
ordinary  temperatures  are  saturated  may  become  under  or 
super-saturated,  causing  sometimes  very  serious  errors  un- 
less constant  care  is  taken.  Even  when  the  solutions  are 
kept  in  bottles  coated  on  the  inside  with  sugar  and  almost 
filled  with  it,  it  has  been  known,  in  consequence  of  a  sud- 
den fall  in  the  temperature  of  the  laboratory,  that  the 
liquids,  though  not  actually  depositing  in  the  storage  bot- 
tles, were  in  a  state  of  supersaturation,  and  as  soon  as  a 
solid  body  was  shaken  with  them,  such  as  the  raw  sugar  to 
be  assayed,  an  immediate  deposit  of  sugar  was  formed, 
sufficient  to  raise  the  test  from  5  per  cent,  to  8  per  cent, 
above  the  true  amount.  In  case  the  solution  is  in  this  con- 
dition, or  by  a  rise  in  temperature  becomes  capable  of  dis- 
solving more  cane-sugar,  the  difficulty  may  be  surmounted 
by  agitating  briskly  a  portion  of  the  solution  for  five 
minutes  with  a  large  excess  of  powdered  sugar  before 


DUMAS'S  METHOD.  247 

using.  It  is  important  to  observe,  also,  that  the  contents 
of  the  washing-flask  A  should  remain  at  the  same  tempe- 
rature, which  should  be  the  same  as  that  of  the  solutions, 
throughout  the  operation ;  direct  handling  is  therefore  as 
much  as  possible  to  be  avoided. 

In  consequence  of  the  time  necessary  for  a  reliable  de- 
termination by  this  method,  or  the  misleading  results  of 
the  estimation  made  in  inexperienced  or  incompetent  hands, 
the  Payen-Scheibler  method  has  never  been  generally 
used  as  a  guide  to  the  buyer  of  raw  sugars,  though  it  de- 
serves to  be.* 

METHOD   OF  DUMAS. 

M.  Dumas  found  that  alcohol  of  85  per  cent,  by  volume, 
containing  fifty  grammes  of  strong  acetic  acid  to  the  litre, 
when  saturated  with  cane-sugar,  marked  74°  on  the  alco- 
holometer of  Gay-Lussac.  For  testing  a  sample  of  sugar, 
100  c.c.  of  the  normal  liquor,  prepared  as  above,  is  agitated 
with  50  grammes  of  the  sugar  to  be  tested,  the  solution 
filtered,  and  the  areometer  floated  in  it.  If  it  marks  74°, 
the  sugar  contains  100  per  cent,  pure  sugar  ;  if  it  descends 
to  69°,  the  percentage  is  95.  Each  degree  lost  by  the  areo- 
meter corresponds  to  one  per  cent,  less  in  the  titre  of  the 
sugar. 

For  sugars  of  88  per  cent,  and  upward  this  process  may 
be  made  to  give  good  results,  but  for  lower  products  the 

*  Lotman  (Stammer's  Jahresb.,  xiii.  156)  has  made  an  extensive  series  of 
analyses  of  raw  beet  and  cane  sugars,  in  which  he  compares  the  yield  according 
to  Scheibler's  method  with  that  by  the  method  of  coefficients.  '|'he  results  show 
that,  with  a  few  exceptions,  Scheibler's  yield  is  from  .20  per  cent,  to  10.15  per 
cent,  higher  than  by  the  latter  method,  the  difference  increasing  as  the  sugars 
become  lower  in  grade  by  a  pretty  even  ratio. 


248  ANALYSIS  OF  RAW  SUGAR. 

results  are  unreliable.  P.  Casamajor*  has  proposed  a 
modification  of  Dumas' s  method,  which  he  highly  recom- 
mends as  giving  good  results  on  all  classes  of  raw  sugars 
except  melados,  or  those  containing  a  similar  amount  of 
water.  He  prepares  the  saturated  alcoholic  solution  by 
agitating  methylic  alcoJiol  of  83J°  Tralles  with  powdered 
sugar.  The  solution,  when  fully  saturated,  marks  77.1°  at 
15°  C.  on  the  alcoholometer.  The  process  for  testing  raw 
sugars  is  carried  out  as  follows  :  19.8  grammes  of  the  sugar 
are  weighed,  well  pulverized,  and  mixed  in  a  mortar,  as 
quickly  as  possible  to  avoid  evaporation,  with  50c.c.  of  the 
standard  solution  ;  the  mixture  is  poured  upon  a  filter,  and 
the  density  of  the  filtrate  is  taken  with  the  areometer.  To 
the  degree  of  the  alcoholometer,  corrected  for  temperature, 
is  added  the  difference  between  100  and  the  alcoholometric 
degree  of  the  standard  solution.  The  sum  represents  the 
percentage  of  cane-sugar  sought. 

The  readings  of  the  Tralles  instrument  must  be  reduced 
to  15°  C. ;  and  to  do  this,  for  solutions  between  60°  and  70°, 
the  number  of  degrees  of  temperature  above  15°  C.  are 
multiplied  by  .37,  and  the  product  subtracted  from  the  ori- 
ginal reading  of  the  areometer ;  for  solutions  above  70°  the 
factor  is  .36,  and  for  those  below  60°  the  factor  becomes 
.38.  It  is  also  advisable  to  make  a  correction  on  account 
of  the  volume  of  the  normal  solution  used :  At 

15°  C.  19.8  grammes  of  sugar  taken  for  a  vol.  of  50       c.c. 
20°  "      "  "  "  "  u         50.25    " 

25°  «      «  "  "  "  "         50.5      " 

30°  "      "  *         "  "  "  "         50.8      " 

35°  "      "  "  "  "  "         51.2      " 

*Jour.  of  Amer.  Chem.  Soc.,  1879,  vol.  i.  No.  6. 


DUMAS'S  METHOD.  249 

For  further  details  the  reader  is  referred  to  the  author's 
paper,  *  which  states  that  the  results  obtained  by  this  pro- 
cess, even  on  very  low  grade  sugars,  agree  closely  with  du- 
plicate assays  made  with  the  optical  saccharimeter. 

*  Cliem.  News,  xl.  74  et  sea. 


CHAPTER  X. 

ANALYSIS   OF  MOLASSES   AND   SYRUPS. 

UNDER  this  head  may  be  included  all  sugar  solutions 
above  a  density  of  15°  or  20°  Baume,  such  as  the  brown 
and  filtered  liquors  of  the  refinery,  and  the  heavy  syrups 
and  molasses  of  the  cane  and  beet  sugar  manufacture. 

Estimation  of  the  Cane-Sugar.— This  estimation  is 
made  with  the  saccharimeter,  as  described  under  RAW 
SUGAR.  The  solutions  should  be  weighed  as  quickly  as 
possible  to  avoid  evaporation.  Molasses  and  impure 
syrups  in  general  require  a  rather  large  quantity  of  lead 
solution  and  bone-black  for  decolorization.  In  some  cases 
the  ordinary  method  of  procedure  fails  to  give  a  solution 
light  enough  to  admit  of  a  saccharimetric  reading,  and  it 
becomes  necessary  to  either  use  the  half -normal  solution  or 
the  half -tube  (100  mm.);  the  reading  in  either  case  must 
be  multiplied  by  2.  When  these  means  fail,  it  is  best  to 
proceed  as  follows  :  Weigh  three  times  the  normal  quanti- 
ty, dilute  to  300  c.c.  after  adding  lead  solution,  and  filter. 
The  solution,  if  still  too  dark,  is  submitted  to  a  further  fil- 
tration through  a  tube  containing  well-dried  bone-black  in 
grains,  care  being  taken  to  reject  the  first  third  of  the  fil- 
trate, as  some  sugar  is  retained  by  the  char.* 

In  beet-sugar  solutions  there  are  generally  impurities 
which  affect  the  polarized  ray  sufficiently  to  cause  the 

*  If  the  prepared  black  described  on  page  168  is  used,  the  filtration  with  a 
tube  is  rarely  or  never  necessary. 

250 


ESTIMATION  OF  CANE-SUGAE.  251 

estimation  of  sugar  with  the  saccharimeter  to  be  more  or 
less  incorrect.  These  impurities  are  : 

Malic  acid.      Polarizing  to  the  left. 
Aspartic  acid  "  " 

(in  alkaline  solution). 

Invert-sugar.  "                " 

Metapectic  acid.  "               " 

Beet-gum.  "                " 

Dextran. -  "         the  right. 

Asparagine.  " 
Aspartic  acid 
(in  acid  solution). 

Glutaminic  acid.  "  " 

The  dextran  and  the  beet-gum  have  a  very  high  rotatory 
power. 

Eissfeldt  and  Follenius*  have  published  a  process  (for 
beet-juice)  whereby  these  interfering  impurities  are  either 
destroyed  or  precipitated,  by  warming  the  solution  to  be 
tested  successively  with  alkaline  solution  of  copper  oxide 
containing  a  large  excess  of  alkali,  solutions  of  basic  ace- 
tate of  lead,  and  ferrocyanide  of  potassium,  filtering,  and 
polarizing.  The  results  are  said  to  be  good. 

Sickelfalso  weighs  13.024  grammes  beet- juice,  adds  1 
c.c.  of  lead  solution,  and  makes  the  liquid  up  to  50  c.c. 
with  absolute  alcohol,  filters,  and  polarizes.  The  aspara- 
gine,  aspartic  acid,  malic  acid,  gum,  and  dextran  remain  in 
the  precipitate,  while  the  presence  of  the  alcohol  neutral- 
izes the  rotatory  effect  of  invert- sugar. 

Tannic  acid  added  to  the  warmed  sugar  solution  precipi- 

*Zeit.  f.  Rubenz.,  1877,  728.  \Ibid.,  1877,  779. 


252  ANALYSIS  OF  MOLASSES  AND  SYRUPS. 

tates  many  of  the  bodies  which  are  optically  active.  When 
this  agent  is  used,  basic  lead  acetate,  in  quantity  more  than 
sufficient  to  precipitate  all  of  the  tannic  acid,  must  be  add- 
ed after  the  latter.  The  tannic  acid  solution  is  prepared 
by  dissolving  50  grammes  of  tannin  in  200  c.c.  of  90  per 
cent,  alcohol,  and  diluting  to  one  litre.  On  account  of  the 
large  precipitate  formed  when  tannin  is  used  in  connection 
with  lead  in  very  low  products,  the  results  are  apt  to  be 
too  high  from  the  influence  of  the  precipitate  (page  166).* 
Clerget's  method  is  hardly  to  be  recommended  to  meet  the 
difficulties  in  the  case  of  optically-interfering  impurities. 
Where  the  sugar  is  to  be  estimated  with  accuracy  it  will  be 
advisable  to  have  recourse  to  the  method  of  inversion  and 
estimation  by  Fehling's  solution  (estimation  of  cane-sugar, 
page  182).  When  the  saccharine  material  is  alkaline  from 
the  presence  of  caustic  lime  or  alkalies,  the  solution  should 
be  barely  acidified  by  acetic  acid  before  the  addition  of  the 
lead  acetate,  in  order  to  neutralize  the  effect  which  alkalies 
have  upon  the  polarized  ray. 

Estimation  of  Invert-Sugar. — As  with  raw  sugar, 
page  217.  The  solution  for  titration  must  be  dilute. 

Estimation  of  Ash. — As  with  raw  sugar,  page  222. 
The  solution,  after  the  addition  of  sulphuric  acid,  ought  to 
be  heated  cautiously,  for  fear  of  loss  by  spurting. 

Estimation  of  the  Water. — For  purposes  not  requir- 
ing much  accuracy  this  determination  may  be  made  with 
the  Balling  saccharometer,  the  reading  indicating  percent- 
ages of  dry  matter,  which  subtracted  from  100  leaves  the 


*  Champion  and  Pellet  (Sucrerie  Indigene,  xii.  276)  add  10  c.c.  strong  acetic 
acid  to  100  c.c.  of  juice,  or  a  proportional  quantity  to  molasses,  after  the  filtra- 
tion from  the  lead  precipitate  in  the  ordinary  process  of  decolorizing.  This  is 
said  to  completely  neutralize  the  optical  effect  of  asparagine. 


ESTIMATION  OF  WATER.  253 

water.  For  an  accurate  determination  of  water  in  sugar 
solutions,  about  twelve  grammes  of  coarse,  well-dried  sand 
are  weighed  in  a  suitable  dish  or  a  watch-glass,  together 
with  a  small  rod  and  a  glass  bulb.  This  gives'  the  first 
weight.  Then  allow  from  one  to  two  grammes  of  the  solu- 
tion to  drop  into  the  bulb  from  a  pipette,  and  reweigh. 
Finally  break  the  bulb  with  a  gentle  pressure,  taking  care 
not  to  allow  any  fragment  to  fall  from  the  dish,  and  care- 
fully mix  the  syrup  with  the  sand  by  means  of  the  rod 
until  a  uniform  mass  is  obtained.  Dry  at  100°  C.  for  four 
or  six  hours.  The  bulbs  can  be  easily  blown  over  a  com- 
mon Bunsen  lamp,  and  should  have  a  small  projecting  neck 
and  be  thin  enough  to  break  easily.  The  diameter  is  about 
12  mm.  Example : 

Weight  of  dish,  sand,  rod,  bulb,  and  syrup.  ..22.121  grins. 
",  "         "         "       "  ..20.104      " 


Syrup  taken  ..........................  2.017      " 

The  ensemble  after  drying  4  hours  ............  21.120      " 

"  "  6     "     ..,  .........  21.119      " 


22.121  -  21.119  =    '1(  -  =  49.67  per  cent,  water. 


Estimation    of  Organic  Matter  not    Sugar.—  By 

difference,  or  one  of  the  methods  given  under  raw  sugar. 
Quotient  of  Purity  or  Exponent  —  The  Direct 
Method.  —  The  most  direct,  and  in  general  the  most  conve- 
nient and  reliable,  way  of  obtaining  this  expression  is  to 
divide  the  percentage  of  impure  sugar,  or  total  solid  mat- 
ter, into  the  percentage  of  pure  sugar  multiplied  by  100. 
The  former  is  represented  by  the  degree  Balling  of  the  so- 


254  ANALYSIS  OF  MOLASSES  AND  SYRUPS. 

lution  reduced  to  standard  temperature,  while  the  latter  is 
the  polarization.  The  quotient  expresses  the  percentage  of 
pure  sugar  contained  in  the  dry  substance  —  i.e.,  the  total 
soluble  matter  if  it  were  deprived  of  water. 

Casamajor'1  s  Method.  —  This  has  the  advantage  of  requir- 
ing no  weighing  ;  but  where  a  balance  is  at  hand  the  direct 
method,  is  preferable  both  on  account  of  absolute  accuracy 
as  well  as  the  agreement  of  the  results  among  themselves. 
According  to  the  original  method,*  the  solution  to  be  tested 
is  diluted  so  as  to  stand  between  5°  to  15°  Brix  ;  the  degree 
Brix  is  taken,  corrected  for  temperature,  and  the  solution, 
after  proper  decolorization,  is  polarized  as  it  stands,  with- 
out weighing  or  dilution.  The  polarization  is  multiplied 
by  a  factor  corresponding  to  the  percentage  of  dry  matter 
by  Brix,  the  product  being  the  quotient  sought.  The  cal- 
culation may  be  made  by  the  formulas  — 

O  --  S  v    16-19      m 
Q  '        :  ITxP 


in  which 

D  is  the  degree  Brix, 

P  the  corresponding  specific  gravity, 

S  the  polarization, 

(1)  is  intended  for  use  with  instruments  requiring  the  nor- 
mal weight  16.19  grammes,  and  (2)  with  the  Soleil-Ventzke. 
I  have  found  that  the  results  given  by  this  process  ap- 
proach nearer  those  of  the  direct  metliod,  and  agree  better 
among  themselves,  by  having  the  solution  less  dilute  than 
that  given  above  ;  in  this  case  the  factor  is  decreased.  The 

*  Amer.  Chemist,  vol.  iv.  161. 


QUOTIENT  OF  PURITY.  256 

following  table,  calculated  by  Mr.  Gr.  S.  Eyster,  of  Boston, 
for  use  with,  this  modification  of  the  method,  gives  the  fac- 
tors by  which  the  reading  of  the  saccharimeter  is  to  be  in- 
creased, for  the  Soleil-Ventzke  instrument.  Example  : 

Reading  of  saccharimeter 50. 1 

Corrected  degree  Brix 25.7 

Then  from  table — 

Factor  for  25.7°  =  .914 

50.1  X  .914  =  45.79  quotient. 

The  solutions  should  be  taken  as  strong  as  it  is  conve- 
nient, up  to  27°  Brix. 


256 


ANALYSIS  OP  MOLASSES  AND  SYRUPS. 


I  S 


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CALCULATION  TO  DRY  SUBSTANCE.  257 

The  estimation  of  the  quotient  of  purity  is  of  great  value 
in  the  various  stages  of  the  manufacturing  and  refining  of 
sugar,  showing  as  it  does,  in  a  single  figure,  the  proportion 
of  pure  sugar  to  impurities.  It  is  pre-eminently  the  test 
for  the  refiner,  who  in  general  does  not  wish  to  know  how 
mucli  sugar  lie  has  in  a  given  solution,  but  how  pure  it  is  ; 
its  value  for  his  purposes  is  altogether  independent  of  the 
amount  of  water  contained.  To  the  buyer  or  seller,  on  the 
contrary,  a  knowledge  of  the  percentage  of  pure  sugar  in 
the  sample  as  it  stands,  otherwise  known  as  the  (i  direct 
test"  or  the  " polarization,"  is  of  the  greatest  importance, 
and  the  percentage  of  water  has  a  direct  bearing  upon  it. 

Calculation  of  the  Results  of  an  Analysis  into  Equiva- 
lents in  tlie  Dry  Substance. — It  is  often  desirable  for  pur- 
poses of  comparison  to  have  the  results  of  an  analysis 
reduced  to  terms  of  the  dry  substance.  The  reciprocal  of 
the  degree  Brix  multiplied  by  100,  is  a  factor  by  which  the 
percentage  of  sugar,  grape-sugar,  and  ash  is  increased  to 
reduce  them  to  the  basis  of  dry  mass  ;  thus  in  a  syrup  hav- 
ing the  following  composition : 

55°  Brix. 

Cane-sugar 45.00 

Grape-sugar 3.10 

Ash 82 

the  factor  corresponding  to  55  is  1.818 ;  then  in  the  dry 

substance  we  have : 

Sugar 45.00  X  1.818  =  81.81 

Grape-sugar. . .  3.10  X  1.818  =  5.63 
Organic  matter  by  difference. . .  11.07 
Ash 82X1.818=  1.49 

100.00 


258  ANALYSIS  OF  MOLASSES  AND  SYRUPS. 

These  figures  represent  the  quotients  of  purity  respec- 
tively of  the  sugar,  grape-sugar,  organic  matter,  and  ash. 
If  the  dry  substance  is  estimated  by  drying,  instead  of  the 
spindle,  the  results  are,  of  course,  more  accurate.  The 
table  on  page  193  may  be  used  to  obtain  the  factors  neces- 
sary in  the  above  calculation. 

Estimation  of  the  Color. — The  determination  of  the 
color  in  relation  to  the  sugar  is  made  according  to  direc- 
tions given  under  Raw  Sugar,  page  229.  For  sugar  solu- 
tions, however,  it  is  generally  only  necessary  to  estimate 
the  color  reduced  to  the  normal  standard  of  the  colori- 
meter. 

Estimation  of  the  Alkalinity. — Products  of  the  beet- 
sugar  manufacture  often  contain  caustic  lime  or  alkalies. 
When  these  bodies  are  present  in  sufficient  amount,  it  be- 
comes necessary  to  determine  them.  For  this  purpose  a 
standard  alkaline  solution  is  made  by  dissolving  exactly 
53  grammes  of  pure  sodium  carbonate,  that  has  been  heated 
some  time  to  drive  off  moisture,  in  water,  and  diluting  to 
one  litre.  A  standard  acid  is  also  prepared  by  mixing  140 
grammes  of  nitric  acid,  sp.  gr.  1.385,  or  an  equivalent 
amount  of  any  other  strength,  with  water,  and  diluting  to 
about  1,100  c.c.  The  relation  between  the  acid  and  alkali  is 
now  found  by  titration,  using  litmus  or  cochineal  solution 
as  an  indicator.  Suppose  20  c.c.  of  acid  saturates  22  c.c. 
of  alkali ;  then  to  make  the  acid  solution  normal — that  is, 
to  contain  in  one  litre  the  number  of  grammes  of  the  body 
dissolved  corresponding  to  its  combining  weight  (such  so- 
lutions will  consequently  saturate  each  other  volume  for 
volume) — every  20  c.c.  of  acid  must  be  diluted  with  two 
c.c.  of  water  to  bring  it  to  the  strength  of  the  alkali,  or  for 
one  litre  2  X  50  =  100  c.c.  To  one  litre  of  the  acid  solu- 


ESTIMATION  OF  COLOR.  259 

tion  is  added,  accordingly,  100  c.c.  of  water,  and  the  ir/ 
ture  well  shaken. 

Molasses  and  heavy  syrups  are  often  too  much  colored 
allow  of  the  use  of  litmus  or  cochineal  solutions,  so  th~u 
the  point  of  saturation  has  to  be  determined  with  delicate 
litmus-paper. 

Seventy-five  grammes  of  molasses  are  weighed  and  di- 
luted with  water  to  250  c.c.;  two  portions  of  100  c.c.  each, 
equivalent  to  30  grammes  of  the  molasses,  are  taken  out 
for  trial  with  the  acid  solution,  the  first  to  obtain  an  ap- 
proximation of  the  alkalinity,  and  the  second  for  a  sepa- 
rate and  more  accurate  determination.  The  alkalinity  is 
generally  calculated  in  terms  of  calcic  oxide  CaO. 

1  c.c.  of  the  test  acid  =  .028  gramme  CaO. 


CHAPTER   XL 

Analysis  of  the  Cane  and  Cane-Juice. 

THE    CANE. 

Estimation  of  Caiie-Sugar.— It  is  difficult  to  obtain 
a  sample  faithfully  representing  the  whole  cane,  as  the 
amount  of  sugar  differs  in  various  parts.  This  variation  is 
particularly  marked  at  the  joints.  It  is  best  to  take  three 
portions  between  the  joints — from  the  base,  top,  and  middle 

Fig.  36- 


of  the  cane,  together  with  one  of  the  joints  ;  slice  the 
pieces  and  press  out  the  juice  in  a  small  metallic  roller- 
press  (Fig.  36),  moistening  the  pressed  cane  with  hot  water 
two  or  three  times,  and  renewing  the  pressure  to  wash  out 
the  sugar  contained  as  closely  as  possible.  The  juice  from 
the  press  is  diluted  to  the  smallest  number  of  cubic 
centimetres  that  it  will  be  convenient  to  calculate  upon. 
For  example :  Eight  times  the  normal  quantity  for  the 
Ventzke-Scheibler  instrument,  equal  to  208.4  grammes  of 
the  cane,  is  weighed,  pressed,  and  washed  until  about  380 
c.c,  of  juice  is  obtained.  This,  for  convenience,  is  diluted 

260 


CANE-JUICE. 

to  400  c.c.  after  the  addition  of  lead  solution,  filtered,  and 
polarized.  If  the  polarization  is  32,  then,  as  eight  times 

OO 

the  normal  was  weighed,  —  =  4,  which  is  multiplied  by 

o 

4,  on  account  of  the  dilution  to  400  c.c.  instead  of  100  c.c., 
the  standard  volume  gives  16.  This  is  the  percentage  of 
cane-sugar  in  the  sample  treated. 

The  sugar  may  also  be  estimated  by  extraction  with  alco- 
hol (page  180)  on  the  dried  assay. 

The  grape-sugar  may  be  determined  in  a  measured  por- 
tion of  the  juice  pressed  from  the  cane,  before  the  addition 
of  lead  solution  or  after  its  removal  by  sulphurous  acid. 
See  estimation  of  invert-sugar  * 

The  asli  and  water  are  estimated  in  the  manner  already 
described  in  other  places.  It  has  only  to  be  remarked  that 
the  slices  should  be  made  quite  thin  to  ensure  good  drying, 
which  is  commenced  at  a  temperature  of  80°,  and  gradually 
raised  to  110°. 

CANE-JUICE. 

The  total  impure  sugar  is  estimated  by  the  Brix  sac- 
charometer.  Vivien's  areometer  (page  115)  may  also  be 
found  useful  for  this  purpose.  For  hot  countries,  where 
cane- juice  has  in  all  cases  to  be  tested,  it  is  well  to  have 
hydrometers  standardized  at  25°  C.,  instead  of  15°  or  17£°, 
as  is  the  usual  practice. 

The  Cane-Sugar  is  estimated  by  the  saccharimeter, 
two  or  three  times  the  normal  quantity  being  weighed. 
The  sugar  can  be  more  quickly  determined,  however,  in 
cane-juice  or  any  other  weak  saccharine  solution  by 
Ventzke's  process,  which  dispenses  with  the  weighing. 
This  method  is  carried  out  by  taking  the  density  of  the 


262  ANALYSIS  OF  THE  CANE  AND  CANE-JUICE. 

juice  with  the  Brix  spindle,  finding  the  corresponding  spe- 
cific gravity  from  the  table  on  page  116,  and  calculating  the 
percentage  of  sugar  according  to  the  following  formulas  : 

P0<  ..2606  __          ( 
D 

P  X  .1619  _ 
~~ 


P  X  .1500 

TT~ 

in  which  P  is  the  polarization  of  the  juice  as  it  stands 
without  weighing  ;  D  —  the  density,  and  S  the  percentage 
of  sugar.  Formula  (1)  is  for  use  with  the  Ventzke-Scheib- 
ler  saccharimeter,  (2)  with  the  Soleil-Duboscq,  and  (3)  for 
those  instruments  of  which  fifteen  grammes  is  the  normal 
weight.  If  the  juice  needs  an  addition  of  lead,  it  is  filled 
into  a  100  c.c.  flask,  and  a  measured  volume  of  the  lead  so- 
lution added  from  a  graduated  pipette,  the  saccharimetric 
reading  being  increased  in  proportion  to  the  dilution.  Ex- 
ample :  Cane-juice  of  10°  Brix  (sp.  gr.  1.04),  to  which  3  c.c. 
of  lead  solution  to  100  c.c.  were  added,  was  found  to  po- 
larize 32  ;  32  +  3  per  cent.  =  32.96.  According  to  the  for- 
mula (1) 

32.96  X  .2605 

~T~04~~         -  ®-%5  per  cent,  cane-  sugar. 

A  table  is  herewith  given,  reckoned  according  to  formula 
(1)  for  the  Soleil-Scheibler  saccharimeter,  which  dispenses 
with  the  calculation.  An  example  will  show  the  manner 
of  using  it  :  A  solution  whose  corrected  per  cent,  of  sugar 
by  the  Brix  areometer  is  9.5  polarizes  27  ;  in  the  horizontal 


VENTZKE'S  METHOD. 


263 


column  opposite  9.5,  under  2,  is  found  .502,  which  multi- 
plied by  10  gives 5.020 

Under  7  in  like  manner  occurs ..  1.757 


Percentage  of  cane-sugar =  6.777 


TABLE  FOR  ESTIMATING   THE  PERCENTAGE   OF   SUGAR  BY  WEIGHT,  IN  WEAK 
SUGAR  SOLUTIONS  :  ABRIDGED  FROM  ONE  CALCULATED  BY  OSWALD. 


Degree 
Brix. 

Sp.  Gr. 

Reading  of  the  Saccharimeter. 

• 

2 

3 

4 

5 

6 

7 

8 

9 

IO 

0. 

•  5 

coo 
0019 

.260 
.260 

.520 

.781 
.780 

.042 
.040 

.302 

.300 

.563 
.560 

-823 
.820 

2.084 
2.080 

2-344 
2.340 

2.605 
2.600 

.0 

0039 

.259 

•  519 

.778 

.038 

-297 

•557 

.816 

2.0/6 

2-335 

2-595 

•  5 

.oosS 

.259 

.518 

•in 

.036 

.295 

•554 

.813 

2.072 

2-331 

2.590 

.0 

-5 

0078 
0097 

3 

•517 
.516 

•775 
•774 

•034 
.032 

.292 

:^s 

.too 
.£06 

2.068 
2.064 

2.326 
2.322 

2.  #5 

2.580 

.0 

0117 

•257 

•515 

.772 

.020 

.287 

'-545 

.802 

2.060 

2.317 

2-575 

•  5 

01^7     i 

.2=7 

.514 

•771 

.028 

-285 

•  542 

•799 

2.056 

2-313 

2.570 

<  .0 

0157 

.256 

.513 

.769 

.026 

.282 

•539 

•795 

2.052 

2-308 

2.565 

L  .  5 

0177 

.256 

.512 

.768 

.024 

.280 

.536 

.792 

2.048 

2.304 

2-559 

5.0 

0197 

•255 

.511 

.766 

.022 

.277 

•533 

.788 

2.044 

2.299 

2-554 

5-5 

0213 

•255 

.510 

.765 

.020 

•  275 

•530 

.785 

2.040 

2-295 

2-549 

6.0 

0237 

.254 

•5°9 

.763 

.018 

.272 

.527 

.781 

2.036 

2.2QO 

2-544 

6-5 

0257 

•254 

.508 

.762 

.Ol6 

.270 

.524 

•  778 

2.032 

2.285 

2.539 

K 

0278 
0298 

•253 
•253 

8 

.760 
.738 

.014 
.012 

I 

•521 
.518 

•774 
.771 

2.027 
2.023 

2.281 
2.276 

2-534 

8.0 

8-5 

0319 
°339 

.252 
.252 

.505 

.504 

•  757 
.756 

.OIO 
.008 

.262 
.260 

!sia 

.767 
.763 

.019 

.015 

2  '267 

2  !$24 

2.519 

9.0 

0360 

.251 

•5°3 

•  754 

.006 

•  257 

.509 

.760 

.Oil 

2.  263 

2.514 

9-5 

0380 

.251 

.502 

•733 

.004 

-255 

.506 

•757 

.007 

2.258 

2.509 

10.  0 

0410 

.250 

.501 

•751 

.002 

.252 

-503 

•  7?3 

.003 

2.254 

2.504 

10.5 

0422 

.250 

.500 

-750 

.000 

.250 

.750 

.999 

2.249 

2.499 

II.  0 

0443 

.249 

•499 

.748 

•998 

.247 

•497 

.746 

•995 

2.245 

2.494 

11.5 

12.0 

0464 
0485 

:1$ 

.498 
•497 

•  747 
•  745 

•994 

.245 
.242 

•494 

•  743 
•739 

.991 
.987 

2.240 
2.236 

2.489 
2.484 

12.5 

o=;c6 

.248 

.496 

•  744 

•992 

.240 

.488 

•735 

•  983 

2.231 

2-479 

13.0 

0528 

•  247 

•495 

•  742 

.900 

-237 

.484 

-732 

•979 

2.227 

2.474 

13-5 

14.0 

.0549 
.0^70 

.247 
.246 

•494 
•493 

•  741 
•  739 

.988 

m 

-235 
.232 

.482 
-479 

.728 
•725 

•975 
.971 

2.222 
2.218 

2.469 
2.464 

14.5 

.0^91 

.246 

.492 

•738 

.984 

.230 

.476 

.722 

.967 

2.213 

2-459 

15.0 

.0613 

•  245 

.491 

•  736 

.982 

.227 

•473 

.718 

-963 

2.209 

2-454 

15-5 

.0635 

•245 

•735 

.980 

.225 

.470 

.714 

•959 

2.204 

2.449 

ID.O 

.0657 

•  244 

.480 

•  733 

.978 

.222 

.467 

.711 

•9V 

2.200 

2.444 

J6.5 

.0678 

.244 

.488 

•  732 

.976 

.220 

•464 

.708 

-951 

2.195 

2-439 

17.0 

.0700 

•243 

.487 

•730 

•974 

.217 

.461 

.704 

.948 

2.IQI 

2-434 

.0722 

•243 

.486 

.729 

•972 

.215 

.458 

.701 

-944 

2.186 

2.429 

js'.l 

•0744 
.0765 

.242 
.242 

-485 
.484 

a 

.970 
.968 

.212 

.2IO 

•455 
.452 

.697 
.694 

2.182 
2.178 

2.424 
2.420 

19.0 

.0787 

.241 

.724 

.966 

.207 

.6c,0 

•  932 

2.173 

2.415 

19.5 

20.0 

.0810 

.241 
.240 

:Js2 
.481 

•723 
.721 

.964 
.962 

.205 

.202 

•443 

.687 
.683 

.928 
.924 

2.169 
2.164 

2.410 
2.405 

20.5 
21.0 

'.087^ 

.240 
•  239 

.480 

•479 

.720 

.718 

.960 

3 

.200 
.197 

.440 
•437 

.680 
.676 

.920 
.916 

2.l6o 

2.155 

2.400 
2-395 

21.5 

.0900 

.470 

.717 

.956 

.195 

•434 

•28 

.912 

2.  HI 

2.390 

22.0 

.0923 

.238 

•477 

•715 

•954 

.192 

•431 

.660      .908 

2.146 

2.385 

22.5 

,0046 

.238 

.476 

.714 

•952 

.428 

.666  j       .904 

2.142 

2.380 

23-0 

'^ 

•237 

•475 

.712 

.950 

A 

1.425 

.662       1.900 

2.137 

2-375 

Grape-Sugar. — (See  chapter  x.) 
AsTi. — (See  chapter  x.) 


264  ANALYSIS  OF  THE  CANE  AND  CANE-JUICE. 

Estimation  of  Water.— By  the  Brix  spindle  or  by  dry- 
ing, according  to  the  accuracy  required  (page  252). 

The  quotient  of  purity  is  a  very  useful  determination, 
and  may  be  made  by  the  direct  method: 

Pol.  X  100 


CHAPTER  XII. 

Analysis  of  tlie  Beet  and  Beet-Juice. 

THE    BEET. 

Preparation  of  the  Sample.— The  top  and  small  radi- 
cles are  cut  off,  and  tlie  beet  is  washed  to  free  from  mecha- 
nical impurities,  being  dried  with  a  coarse  towel.  If  de- 
sired, the  weight  "before  and  after  this  treatment  may  be 
taken.  If  a  single  beet  is  to  be  operated  upon,  the  whole, 
after  the  above  preparation,  is  reduced  to  a  fine  pulp  by 
grating  or  any  other  means.  For  a  sample  representing  a 
quantity  of  beets  or  the  growth  of  a  field,  it  is  necessary 
to  take  a  number  of  roots  differing  in  size  and  variety. 
Beets  taken  from  the  same  field,  and  apparently  submitted 
to  the  same  conditions,  are  found  to  vary  a  great  deal  in 
their  saccharine  richness. 

By  successive  slices,  made  parallel  to  the  axis  of  the 
beet,  cut  out  a  square  prism,  of  such  thickness  as  will  be 
determined  by  the  size  of  the  roots.  Fig.  37  Fig§  37t 
will  illustrate  this.  The  dotted  line  represents 
in  projection  the  prism.  The  different  por- 
tions thus  obtained  from  all  the  roots  consti- 
tuting the  average  are  reduced  to  pulp  and 
mixed  together.  Champonnois  has  invented  a 
boring  rape  which  serves  very  well  to  cut  out 
a  portion  of  the  beet  as  above  described,  and 
which  pulps  it  at  the  same  time  (Fig.  38). 

265 


266  ANALYSIS  OF  THE  BEET  AND  BEET-JUICE. 

Estimation  of  Cane-Sugar. — About  200  grammes 
of  the  pulp  are  placed  in  a  small  filtering-bag  and  pressed  in 
a  hand-press  slowly  until  the  juice  ceases  to  flow  with  the 
strongest  pressure  obtainable  ;  the  marc  is  then  moistened 
with  boiling  water,  the  pressure  renewed,  and  this  opera- 
tion repeated  until  all  soluble  matter  has  been  extracted 
and  the  residue  is  dry,  care  being  taken  to  avoid  undue  di- 
lution of  the  solution.  Three  to  four  cubic  centimetres  of 
tannin  solution  are  added,  and  about  three  times  that  volume 

Fig.  38- 


of  lead  solution,  and  the  whole  made  up  to  an  exact 
volume,  filtered,  and  a  portion  polarized.  Any  of  the 
modifications  suggested  in  the  case  of  molasses  (page  251) 
may  be  tried.  The  calculation  is  in  all  respects  similar  to 
that  for  estimating  the,  sugar  in  the  cane. 

Scheibler's  Method  for  estimating  Sugar  in  the 
Beet.*— The  estimation,  as  given  above,  will  show  only  ap- 
proximately the  amount  of  sugar,  on  account  of  impurities 
present  in  the  juice  obtained,  which  have  a  considerable 
effect  upon  the  polarized  ray— as  well  as  the  generally  im- 
perfect extraction  of  the  sugar.  Scheibler's  process, 

*  German  Patent,  No.  3573,  Stammer's  Jahrb.,  1879. 


SCHEIBLER'S  METHOD. 


26? 


Fig.  38K. 


though  requiring  spe- 
cial apparatus,  avoids 
these  errors,  and  gives 
results  very  near  the 
truth.  It  is  essentially 
an  extraction  of  the 
sugar  from  the  finely- 
divided  beet  without 
previous  drying,  by 
means  of  alcohol,  in 
the  heat. 

The  apparatus  is 
shown  in  Fig.  38J-.  D 
is  an  upright  glass  con- 
denser fitted  tightly  to 
A  by  a  rubber  cork.  A 
and  B  are  glass  tubes  of 
the  form  shown,  A  be- 
ing placed  within  B, 
and  making  a  close 
joint  at  the  upper 
ends,  the  lower  portion 
of  A  being  free  and 
open.  Near  the  top  of 
the  latter  are  two  or 
more  openings,  five  to 
six  mm.  in  diameter, 
o  o,  communicating  be-  ifj 
tween  the  annular 
space  and  the  interior 
of  A.  B  is  fastened  with  a  rubber  cork  to  the  flask  e, 
which  is  graduated  to  50  c.c.  The  narrowed  end  of  B  ex- 


268  ANALYSIS  OF  THE  BEET  AND  BEET-JUICE. 

tends  some  distance  into  £,  in  order  that  none  of  the  boil- 
ing sugar  solution  may  be  spurted  into  the  former.  In  the 
cylinder  A  is  placed  a  small  filter,  a,  which  may  be  of  cot- 
ton, felt,  or  other  suitable  material. 

For  the  execution  of  the  test  from  20  to  25  grammes 
beet-pulp  are  placed  in  A,  which  has  been  previously  tared, 
by  means  of  a  long-stemmed  funnel,  so  that  the  mass  fills 
the  tube  nearly  to  o  o.  A  is  then  reweighed,  and  the  dif- 
ference of  the  two  weighings  gives  the  amount  of  assay 
taken.  The  cylinders  A  and  B  are  now  adjusted  as  shown 
in  the  cut,  and  the  condenser  fixed  in  position.  Now  25 
c.c.  alcohol  of  90  to  94  per  cent.  Tralles  (.8339  to  .820  sp. 
gr.)  are  placed  in  the  flask,  and  by  means  of  a  sand  or  water 
bath  heated  to  boiling.  It  is  perhaps  better  that  the  alco- 
hol should  be  added  through  the  top  of  the  condenser  at 
^,  through  which  it  passes  to  the  beet-pulp  and  falls  in  c. 
The  vapor  from  the  boiling  alcohol,  ascending  into  the 
space  between  A  and  B,  passes  through  o  o,  and  is  liquefied 
in  the  condenser  (kept  cool  by  a  stream  of  water),  from 
which  it  drops  in  A,  and,  coming  in  contact  with  the  assay, 
extracts  the  sugar,  the  solution  dropping  into  the  flask, 
where  it  parts  with  its  alcohol,  which  is  again  made  to  pass 
through  the  substance  to  be  extracted.  The  flame  should 
be  so  regulated  that  the  drops  from  A  should  succeed  each 
other  at  regular  intervals,  and  not  too  quickly.  As  a  rule, 
from  a  half  to  three-quarters  of  an  hour  s  boiling  is  suffi- 
cient to  complete  the  operation,  after  which  the  apparatus 
is  allowed  to  cool,  the  last  drops  of  the  solution  from  A 
being  received  in  the  flask,  which  is  filled  to  the  mark  with 
distilled  water,  after  the  addition  of  a  few  drops  of  lead, 
filtered,  and  the  sugar  estimated  with  the  saccharimeter. 
The  alcoholic  sugar  solution,  after  dilution  to  50  c.c., 


ESTIMATION  OF  MARC.  269 

should  show  about  41  per  cent.  Tralles.  For  many  varie- 
ties of  beets  the  strengths  given  for  the  alcohol  cannot  be 
strictly  adhered  to,  as  when  the  latter  is  too  dilute  a  trou- 
blesome frothing  takes  place  on  boiling. 

According  to  Scheibler  and  Tollens  (loc.  cit.\  the  con- 
tinued boiling  of  the  alcoholic  solution  causes  no  sensible 
alteration  of  the  sugar  dissolved,  even  when  the  beets  ope- 
rated upon  are  slightly  acid.  The  method  has  been  ex- 
haustively and  critically  examined  by  Tollens  *  and  others, 
with  the  result  of  establishing  its  substantial  accuracy  as 
showing  the  absolute  amount  of  sugar  in  the  beet,  and  its 
great  superiority  over  processes  previously  in  use. 

Estimation  of  the  Marc  and  the  Amount  of  Juice. 

« 

-Twenty  grammes  of  the  pulp  are  made  into  a  thin  paste 
with  boiling  water,  poured  upon  a  weighed  filter,  and  tho- 
roughly washed,  with  the  aid  of  a  vacuum  if  necessary. 
The  filter  is  then  dried  at  110°.  Example  : 

Watch-glasses  +  filter  +  marc  at  110°  =  22.100 
"  +     "    at  110°  =  21.260 

Weight  of  marc 840 

.140  X  100  =  4  3  nt 

20 

The  percentage  of  marc  subtracted  from  100  gives  the  per- 
centage of  juice,  as 

100  —  4.2  =  95.80  per  cent,  juice. 

The  amount  of  juice  may  be  obtained  by  an  indirect 
method  which  gives  results  agreeing  very  well  with  the 
above.  The  water  is  determined  in  the  pulp  by  drying, 


*  Zeit.  /.  Rubenz.,  May,  1880;  Stammer's  Lehrbuch,  Erganzungsbaml,  102. 


270  ANALYSIS  OF  THE  BEET  AND  BEET-JUICE. 

and  also  in  the  juice ;  then  the  percentage  of  juice  is  found 

A 

by  the  formula  -^-  X  100,  in  which  s  is  the  percentage  of 

water  in  the  pulp,  and  S  that  in  the  juice.  The  marc  is  ob- 
tained by  difference. 

Scheibler's  Method. — The  percentage  of  marc,  and 
from  it  that  of  the  juice,  may  be  obtained  with  greater 
accuracy  than  by  the  methods  described,  in  connection  with 
Scheibler's  process  for  determining  the  sugar  in  the  beet 
(page  266).  The  contents  of  the  tube  A,  after  the  extrac- 
tion of  the  sugar,  are  desiccated  bypassing  a  stream  of  dry 
air  through  the  latter,  after  which  it  is  weighed  and  the 
amount  of  marc  calculated.  Scheibler  claims  that  the  re- 

o 

suits  obtained  by  the  formula  -  -  X  100  are  erroneous,  as 

o 

the  direct  polarization  of  the  juice  is  never  quite  correct, 
owing  to  the  presence  of  about  five  per  cent,  of  sugar-free 
water  in  the  beet  (colloidal  water}. 

Grape-Sugar  is  generally  present  in  very  small  quanti- 
ties. To  estimate  it  a  weighed  portion  of  the  pulp  is  ex- 
tracted with  water,  and  the  grape-sugar  determined  in  the 
expressed  liquor  by  Fehling's  method,  with  the  usual  pre- 
cautions (see  estimation  of  dextrose). 

Water  is  determined  by  drying  the  pulp  or  the  thinly- 
sliced  beet  at  100°. 

The  Estimation  of  Ash. — As  in  raw  sugar  (page  222), 


ANALYSIS   OF  BEET-JUICE. 

The  Baume  hydrometer  is  largely  used  to  afford  a  rela- 
tive comparison  as  to  the  value  of  beet- juice.  The  Brix 
spindle  is,  however,  preferable,  in  that  the  readings  corre- 


ANALYSIS  OF  BEET-JUICE.  271 

spond,  within  certain  limits  of  error,  to  the  percentage  of 
impure  sugar  in  solution. 

Estimation  of  Cane-Sugar. — By  the  saccharimeter, 
twice  or  thrice  the  normal  quantity  being  taken  and  di- 
luted up  to  100  c.c.,  after  the  addition  of  about  2  c.c.  tan- 
nin and  6  c.c.  of  lead  solutions.  The  cane-sugar  may  also 
be  readily  determined  by  Ventzke's  method  (page  261). 
As  with  beet-  molasses,  though  in  a  less  degree,  this  estima- 
tion is  rendered  more  or  less  incorrect  by  the  presence  of 
optically  active  impurities  in  the  juice,  For  modifications 
of  the  usual  method  to  be  pursued  to  meet  this  source  of 
error,  see  the  chapter  on  the  analysis  of  molasses  (page 
250). 

Estimation  of  Grape-Sugar. — As  in  the  case  of  the 
beet. 

Estimation  of  the  Ash.— With  sulphuric  acid,  as 
with  the  beet.  The  juice  should  be  carefully  evaporated 
to  avoid  loss,  before  the  charring  takes  place. 

Estimation  of  Water. — By  drying  in  sand  with  bulb 
(page  252)  for  accurate  work,  by  preference  in  vacuo — or 
with  the  Balling  spindle. 

Quotient  of  Purity. — Divide  the  degree  Balling,  cor- 
rected for  temperature,  into  the  percentage  of  cane-sugar 
by  polarization  X  100.  Stammer  gives  as  the  valuation-co- 
efficient ( WertTizaTiT)  of  beet-juice,  an  expression  obtained 
by  multiplying  the  quotient  into  the  percentage  of  cane- 
sugar,  and  dividing  by  100.  This  is  only  useful  for  compa- 
rative purposes. 

Estimation  of  Organic  Matter  not  Sugar. — This  is 
determined  by  difference  or  any  of  the  methods  given  in 
chapter  ix.  Where  the  water  is  estimated  by  the  areome- 
ter the  results  are  always  low,  owing  to  the  error  of  the 


272  ANALYSIS  OF  THE  BEET  AND  BEET-JUICE. 

instrument  in  impure  solutions,  and  consequently  the  mat- 
ters determined  by  difference  are  too  high.  To  correct  this 
error,  Stammer  has  proposed  to  subtract  one-fifth  of  the 
organic  matter  thus  found,  and  add  it  to  the  water.  This 
correction  would  equally  apply  to  all  impure  sugar  solu- 
tions, whether  from  the  beet  or  cane. 

Estimation  of  the  Alkalinity.— On  the  juice  with- 
out dilution  (page  258). 

Estimation  of  the  Color.— As  with  raw  sugar  and 
molasses. 

The  wet  analysis  of  beet- juice  may  be  reduced  to  dry 
substance,  as  shown  on  page  257. 

Note. — The  matter  given  in  relation  to  the  analysis  of 
cane  and  beet  juice  applies  equally  to  any  weak  sugar  solu- 
tion, such  as  the  "  sweet  water"  from  char- washing,  etc. 


CHAPTER  XIII. 

Analysis  of  Waste  Products. 

ANALYSIS   OF   SCUMS   AND   SOLID   RESIDUES. 

THESE  consist  of  the  refinery  scums ;  the  marc  of  the 
beet  freed  from  all  obtainable  sugar  ;  the  bagass,  or  residue 
from  the  cane-presses ;  -and  the  precipitates  produced  in 
the  process  of  carbonatation  and  defecation  in  the  beet- 
sugar  manufacture.  The  only  estimation  commonly  made 
upon  these  bodies  is  that  of  the  sugar.  Before  these  resi- 
dues are  thrown  out  in  the  course  of  the  manufacture,  it  is 
of  considerable  importance  to  make  sure  that  there  is  no 
undue  proportion  of  sugar  present.  They  should  be  test- 
ed systematically,  and  sufficiently  often  to  form  a  proper 
control  of  the  work. 

Refinery  Scum.— This  is  the  matter  caught  in  the 
bag-filters  when  the  crude  solution  of  raw  sugar  is  filtered 
preparatory  to  being  run  upon  the  char.  It  consists  of  the 
insoluble  matters  contained  in  the  raw  sugar,  as  sand, 
foreign  matters  of  all  kinds,  particles  of  cane-fibre,  the 
substances  precipitated  by  caustic  lime  in  defecation,  and 
the  coagulated  albumen  and  bodies  carried  down  with  it, 
when  blood  is  used  in  the  process  of  defecation. 

Estimation  of  Cane-Sugar. — From  a  large  average  sam- 
ple, a  smaller  one  is  prepared  by  taking  out  portions  and 
thoroughly  mixing  them  together.  Weigh  13.04  grammes 
for  the  Ventzke-Scheibler,  or  the  normal  quantity  for  other 

273 


274  ANALYSIS  OF  WASTE  PRODUCTS. 

saccharimeters,  add  enough  boiling  water  to  make  a  uni- 
form paste,  and  gradually  dilute  with  the  hot  water  until 
the  weighing-capsule  is  nearly  full  and  a  uniform  thin 
magma  is  obtained  free  from  lumps  ;  pour  this  upon  a 
filter  in  a  funnel  provided  with  a  filtering- cone,  and  filter 
by  the  aid  of  a  vacuum  into  a  flask  or  cylinder  graduated 
to  100  c.c.,  until  all  the  liquid  has  passed  through;  add 
small  portions  of  boiling  water  at  a  time,  stirring  up  the 
insoluble  matter  on  the  filter  as  much  as  possible  with  the 
stream  from  the  wash-bottle,  and  continue  the  washing  un- 
til the  filtrate  measures  nearly  100  c.c. ;  if  the  solution  is 
alkaline,  barely  acidify  with  acetic  acid,  add  a  few  drops 
of  lead  solution,  allow  to  cool,  fill  to  the  mark,  shake,  add 
a  little  powdered  bone-black,  filter,  and  polarize.  The 
reading  (by  the  Yentzke-Scheibler  instrument),  multiplied 
by  two,  gives  the  percentage  of  cane-sugar.  This  method 
is  accurate  enough  for  nearly  all  purposes ;  but  where 
greater  exactness  is  required  the  scum  may  be  extracted 
with  a  larger  quantity  of  hot  water,  and  the  sugar  deter- 
mined in  an  aliquot  part  of  the  filtrate  after  inversion,  by 
Fehling's  method. 

If  the  grape-sugar  is  to  be  determined,  the  solution  is 
made  to  100  c.c.  before  the  addition  of  the  lead,  and  an  ali- 
quot part  of  it  taken  for  the  grape-sugar  estimation.  From 
the  remainder  a  50  c.c.  flask  is  filled,  a  measured  volume  of 
lead  solution  added,  the  solution  filtered  and  polarized. 
The  reading  must  be  corrected  for  the  dilution  caused  by 
the  addition  of  the  lead. 

The  water  is  determined  by  drying  one  gramme  at  100° 
to  110°  C. 

The  asli  is  determined  by  incineration  without  the  addi- 
tion of  sulphuric  acid. 


CARBONATATION  RESIDUES.  275 

Beet  Marc. — The  cane-sugar  may  be  determined  in  the 
same  manner  as  with  refinery  scums,  or  better  after  Schei- 
bler's  method  with  alcohol  (page  266).  If  the  residue  is 
very  poor  in  sugar,  it  would  be  advisable  to  estimate  the 
latter  by  the  inversion  with,  hydrochloric  acid,  and  Fehl- 
ing's  method,  after  extraction  with  a  large  quantity  of  hot 
water.  The  other  estimations  may  be  made  as  in  the  case 
of  refinery  scums. 

Residues  from  the  Carbonatatioii  Process. — These 
form  the  precipitates  produced  by  adding  a  large  excess  of 
caustic  lime  to  the  sugar  solutions,  and  precipitating  the 
solution  of  calcic  sucrate  with  a  stream  of  carbonic  acid 
gas.  They  are  frequently  alkaline  from  imperfect  carbona- 
tation,  and  the  sugar  contained  is  in  the  state  of  sucrate. 
The  estimation  of  the  cane-sugar  may  be  made  similarly 
to  that  of  refinery  scums,  except  that  it  is  necessary  to 
first  diffuse  the  solid  matter  through  water,  and  pass  a 
stream  of  washed  carbonic  acid  gas  to  break  up  the  combi- 
nation of  the  sugar  with  the  lime  ;  filter  from  the  precipi- 
tated calcium  carbonate,  and  determine  the  sugar  in  the 
filtrate  by  the  saccharimeter,  or  with  alkaline  copper  solu- 
tion after  inversion. 

E.  Perrott  *  gives  a  method  that  is  equally  applicable  to 
the  determination  of  cane-sugar  in  all  sucrates.  One  hun- 
dred grammes  of  substance  are  taken,  mixed  well  with  380 
c.c.  of  water,  at  the  same  time  breaking  up  all  lumps,  and 
20  c.c.  of  carbonate  of  ammonia  solution.  The  mixture  is 
allowed  to  stand  ten  minutes  after  agitation,  and  filtered. 
From  the  filtrate  200  c.c.,  representing  50  grammes  of 
assay,  are  taken,  diluted  to  400  c.c.,  and  the  cane-sugar 
determined  by  Fehling's  method  after  inversion. 

*  Sucrerie  Indigene,  ix.  11. 


276  ANALYSIS  OF  WASTE  PRODUCTS. 

Bagass. — Two  hundred  grammes  are  reduced  to  as  fine 
a  state  of  division  as  possible,  mixed  well  with  boiling  wa- 
ter, placed  in  a  small  filtering-bag,  and  pressed  with  a 
hand-press.  The  washing  is  repeated  with  fresh  portions 
of  water,  and  the  pressing  renewed  until  all  sugar  is  ex- 
tracted. As  the  solution  is  commonly  too  dilute  to  test  to 
advantage  with  the  polariscope,  it  is  best  to  take  an  ali- 
quot part  of  that  obtained,  corresponding  to  a  known 
weight  of  bagass,  and  to  estimate  the  grape-sugar  directly, 
and  the  cane-sugar  after  inversion,  by  Fehling's  method. 

WASTE    WATERS. 

Under  this  head  are  included  the  last  washings  of  the 
bag  and  char  filters,  and  those  of  the  diffusion  and  macera- 
tion processes  of  the  beet-sugar  manufacture.  It  is  espe- 
''illy  important  to  know  when  the  washings  no  longer 
tain  enough  sugar  to  make  it  advantageous  to  save 
them.  Ten  c.c.  of  the  waste  waters  are  evaporated  at  a 
water-bath  heat  in  tared  dishes,  and  the  net  residue  repre- 
sents the  amount  of  solid  matter  contained,  of  which  from 
twenty  to  seventy-five  per  cent,  may  be  sugar.  If  it  is 
wished  to  estimate  the  amount  of  sugar,  a  larger  portion 
is  evaporated  with  the  addition  of  a  few  drops  of  hydro- 
chloric acid,  and  the  amount  of  invert-sugar  determined  by 
Fehling's  method. 

Estimation  of  Cane-Sugar  in  Dilute  Solutions.— 
In  testing  very  dilute  solutions  for  sugar  the  following 
method  of  procedure  may  be  adopted  :  Evaporate  the  solu- 
tion after  careful  neutralization,  if  necessary,  to  from  one- 
fifth  to  one-twentieth  of  its  bulk,  on  a  water-bath  at  a  low 
heat,  and  determine  the  grape-sugar  directly,  and  the  cane- 


ESTIMATION  OF  SUGAR  IN  DILUTE  SOLUTIONS.          277 

sugar  after  inversion  by  Fehling's  method.  As  a  rule,  for 
very  dilute  solutions,  the  mere  presence  of  sugar  of  any 
kind  is  sought  to  be  demonstrated,  so  that  it  is  only  neces- 
sary to  evaporate  with  the  addition  of  a  little  hydrochloric 
acid,  and  determine  the  invert-sugar  found. 


CHAPTER  XIY. 


ANALYSIS   OF   COMMERCIAL   GLUCOSE   OR   STARCH-SUGAR. 

Grape-Sugar  —  Corn-Sugar. 
StarTcezuclcer,  Kornzucker,  Gr. — Sucre  de  Fecule,  Fr. 

THIS  product  is  prepared  from  corn-meal  or  starch, 
either  by  the  action  of  mineral  acids  at  a  boiling  tempera- 
ture, or  by  means  of  diastase.  It  occurs  commercially  in 
three  forms — viz. ,  in  the  condition  of  a  dry  granular  or  fine 
powder  ;  as  a  solid  in  lumps  containing  varying  amounts  of 
water ;  and  as  a  thick  yellowish  or  white  syrup.  The  fol- 
lowing analyses  will  show  the  composition  of  different  va- 
rieties : 

I.  By  Steiner.* 


• 

I. 

ii. 

in. 

IV. 

Water..                    

15  50 

6.00 

13.30 

7.60 

Ash  

.30 

2.  so 

.40 

I.IO 

Dextrose                              .        .    . 

At    AQ 

26  50 

76  oo 

Maltose     ..       

28.OO 

40  ^o 

S  oo 

42.60 

Dextrin  

Q.3O 

IS  QO 

30.80 

Carbohydrates                       .        . 

I    SO 

7  OO 

e  OQ 

8.QO 

Protein  substances     

traces. 

1.  80 

.20 

Acid  (as  SO4H2)     

.08 

.03 

.05 

distinctly 

.  blue. 

100.08 

100.03 

100.25 

IOO.OO 

*  Stammer's  Jahrt.,  1879,  379  ;  Dingier,  ccxxxiii.  262. 

278 


ANALYSES  OP  GLUCOSE. 


279 


The  first  is  of  German  origin,  white  and  soft ;  the  rest  are 
English,  produced  by  the  action  of  dilute  sulphuric  acid 
on  corn-meal  at  high  pressure. 

II. 


Powdered. 

Granulated. 

Lumps. 

Syrup. 

Sugar  by  copper  test.. 
Undetermined  bodies 
Water 

81.63 
9.06 
8  76 

74-27 
Il.Sg 
IT    -2,1 

71.26 

12.57 

T  C    7J 

50 
30 
IQ 

Ash  

.CC 

CQ 

46 

I 

IOO.OO 

IOO.OO 

IOO.OO 

IOO.OO 

In  III.,  the  next  series  of  analyses,  by  Neubauer,  the 
sugar  is  estimated  by  the  fermentation  method : 


I. 

II. 

III. 

IV. 

Fermentable  sugar  

57.20 

63.02 

61.43 

CQ  2=; 

Non-ferment  bodies  (dextrin,  etc.)  
Water  

18.38 

24  42 

13.32 

23.66 

22.45 
16  12 

23-59 

17  16 

IOO.OO 

IOO.OO 

100.00 

100.00 

The  non-fermentable,  or  bodies  classed  as  undetermined, 
consist  of  dextrin,  unaltered  starch,  and,  according  to 
Haarstick,*  of  the  amylin  of  Bechamp.  They  have  a 
high  dextro-rotation. 

The  solid  varieties  of  commercial  glucose  show  Mrotation 
in  a  marked  degree,  while  with  the  syrups  this  property  is 
generally  absent.  The  latter  differ  from  the  former  in  that 
the  conversion  of  the  starch  into  sugar  is  not  carried  so 


*  Stammer's  Jdhrb.,  1876, 176. 


280  ANALYSIS  OF  COMMERCIAL  GLUCOSE. 

far,  and  hence  the  amount  of  organic  matter  not  sugar  in 
them  is  proportionately  large. 


ESTIMATION   OF   THE   SUGAK  BY   FEHLING  S   METHOD. 

On  account  of  the  presence  of  maltose  with  the  dextrose, 
sometimes  in  large  amounts  as  shown  by  Steiner'  s  results, 
this  determination  cannot  show  anything  definite  as  repre- 
senting dextrose.  The  amount  of  copper  oxide  reduced 
by  the  two  sugars  differs  very  much,  100  parts  of  maltose 
reducing  141.5  parts  CuO,  while  the  same  quantity  of  dex- 
trose throws  down  220  parts  CuO.  The  results  of  this  test 
have  accordingly  only  a  relative  value.  As  to  the  action 
of  dextrin  upon  the  heated  copper  liquor,  Kumpf  and 
Heinzerling,*  as  the  result  of  their  investigation,  state  that 
solutions  of  (1)  caustic  soda  and  cupric  sulphate  at  the 
boiling-point  do  not  act  on  dextrin  entirely  free  from  sugar, 
which  corrects  Grerhardt's  observation,  who  asserted  that 
dextrin  caused  a  reduction  of  the  oxide  in  the  sulphate; 
(2)  solutions  of  alkaline  tartrates,  and  Fehling's  solu- 
tion each  act  upon  dextrin,  making  the  results  of  the 
dextrose  estimation  too  high  in  direct  proportion  to  the 
length  of  time  the  heating  is  continued.  When  the  reduc- 
tion is  quickly  effected,  and  the  heating  continues  only  a 
few  minutes,  they  have  found  that  the  error  in  the  estima- 
tion of  dextrose  in  the  presence  of  dextrin  in  starch-sugars 
is  too  small  to  sensibly  affect  the  results. 

The  execution  of  the  test  is  in  all  respects  according  to 
directions  already  given.  See  chapter  viii. 

*  Zeit.  f.  Anal  Chemie,  ix.  358. 


ESTIMATION  BY  FERMENTATION.  281 

ESTIMATION   OF  THE  DEXTROSE    BY   FERMENTATION.* 

A  solution  of  the  sugar  to  be  examined  is  made  contain- 
ing a  known  amount,  and  the  percentage  of  dry  matter  de- 
termined. The  solution  is  then  submitted  to  fermentation 
with  yeast,  and,  after  the  expulsion  of  the  alcohol  and  car- 
bonic acid  formed,  the  percentage  of  dry  matter  is  again 
determined,  and  the  difference  between  the  amounts  of  dry 
substance  estimated  before  and  after  fermentation  gives 
the  sugar  originally  present.  The  results  are  a  little  low 
as  compared  with  those  given  by  Fehling1  s  method,  because 
in  the  vinous  fermentation  all  of  the  sugar  does  not  break 
up  into  alcohol  and  carbonic  acid,  but  aboiit  five  per  cent, 
is  converted  into  glycerin,  succinic  acid,  and  other  bodies, 
which,  being  non-volatile  at  the  temperature  of  boiling 
water,  remain  in  the  liquid  after  the  evaporation. 

Example :  One  hundred  grammes  of  starch-sugar  are 
dissolved,  diluted  to  one  litre,  and  the  specific  gravity 
taken.  Suppose  it  is  1.03  :  we  find  from  Balling's  table 
(page  116)  that  this  corresponds  to  a  percentage  of  dry  sub- 
stance of  7.463,  and  as  100  c.c.  weigh  103  grammes,  100 
grammes  of  the  solution  contain  9.708  grammes  of  the  ori- 
ginal assay,  and 

9.708  :  7.463  ::  100  :  x  =  76.87  per  cent. 
The  composition  of  the  solution,  then,  is 

76.87  per  cent,  dry  substance. 
23.13       "        water. 

100.00 
For  the  fermentation  500  c.c.  of  this  solution  are  taken, 

*  Neubauer,  Wagner's  Jahresb.,  1875,  806. 


ANALYSIS  OF  COMMERCIAL  GLUCOSE. 


a  sufficient  quantity  of  fresh  beer-yeast  added,  and  the 
whole  placed  in  a  fermentation  apparatus  arranged  so  that 
dried  carbonic  acid  can  escape.  Compare  matter  on  page 
181.  The  system  is  then  weighed,  and  allowed  to  remain  at 
the  proper  temperature  for  three  or  four  days  until  the  ac- 
tion is  complete.  This  point  may  be  ascertained  by  weigh- 
ing at  intervals.  When  the  apparatus  ceases  to  lose  weight 
the  operation  may  be  considered  as  finished.  The  liquid 
in  the  flask  is  filtered,  boiled  down  to  one-third  of  its 
volume  to  drive  oif  alcohol,  and,  after  cooling,  made  up  to 
its  original  bulk.  If  the  density  after  fermentation  is 
1.0082,  which  corresponds  to  2.05  percent,  dry  matter,  10X) 
c.c.  weigh  100.82  grammes  and  contain  2.068  grammes  dry 
substance  ;  or  in  500  c.c.,  10.340  grammes.  As  the  500  c.c. 
of  solution  contained  50  grammes  of  the  original  sugar, 

10.340  X  100 
then  —  20.67  per  cent,  unfermen  table  mat- 

ter ;  76.87  —  20.67  =  56.20  per  cent,  of  fermentable  sugar. 


This  is  based  on  the  fact  that  the  impurities  present  in 
commercial  starch-sugar  have  a  greater  density  than  that 
of  the  sugar  contained.  The  process,  though  somewhat 
empirical,  is  said  to  give  results  accurate  enough  for  most 
purposes. 

A  saturated  solution  of  the  sugar  to  be  examined  is  made 
by  adding  a  large  excess  of  it,  in  as  fine  a  state  of  division 
as  possible,  to  water,  and  allowing  the  mixture  to  stand, 
with  frequent  agitation,  for  twelve  hours,  or  until  fully 
saturated.  The  specific  gravity  of  the  clear  solution  thus 
produced  is  obtained  either  by  the  specific-gravity  balance 


ESTIMATION  OF  WATER. 


283 


or  by  weighing  (chapter  v.)     From  this  the  percentage  of 
impurities  may  be  found  in  the  accompanying  table : 


TABLE. 


Density  of  sat. 
solution. 

Per  ct.  of 
impurities:. 

Density  of  sat. 
solution. 

Per  ct.  of 
impurities. 

Density  of  sat. 
solution. 

Per  ct.  of 
impurities. 

.2060 

0 

.2350 

15 

.2587 

30 

.2082 

I 

.2368 

16 

.2603 

31 

.2IO4 

2 

.2386 

17 

.26l8 

32 

.2125 

3 

.2404 

18 

.2633 

33 

.2147 

4 

.2422 

J9 

.2649 

34 

.2169 

5 

.2440 

20 

.2665 

35 

.2l8g 

6 

1.2456 

21 

.2680 

36 

.2208 

7 

•2473 

22 

.2695 

37 

.2228 

8 

.2489 

23 

.2710 

33 

.2247 

9 

.2506 

24 

.2725 

39 

.2267 

10 

.2522 

25 

.2740 

40 

.2284 

ii 

.2535 

26 

•2755 

41 

.2300 

12 

.2548 

27 

.2770 

42 

.2317 

13 

I.256I 

28 

.2785 

43 

•2333 

14      i 

1-2574 

29 

ESTIMATION    OF    THE  WATER. 

Two  to  three  grammes  are  weighed  and  dried  with  sand 
(page  219).  In  the  case  of  solid  glucose,  the  portion  to  be 
tested  is  placed  on  the  weighing-dish,  separated  from  the 
sand,  and  melted  with  a  gentle  heat.  When  liquefied  it  is 
mixed  with  the  sand  in  the  usual  manner. 

The  dextrin  and  other  matters  are  estimated  by  differ- 
ence, after  the  ash  is  determined  by  incineration,  with 
the  addition  of  sulphuric  acid.* 

*  Estimation  of  the  Dextrose  optically. — This  determination  cannot  be 
made  by  the  optical  method,  on  account  of  the  presence  of  a  large  and  varia- 
ble amount  of  dextrin,  maltose,  and  other  bodies,  which  are  optically  active, 
and  whose  specific  rotatory  powers  are  different  from,  and  much  greater  than, 
that  of  dextrose.  The  specific  rotatory  power  of  dextrin  varies  from  [a]  j  =  139° 
to  212° ;  while  that  of  maltose  is  [a]  D  =  139.3°.  If  it  is  desired,  for  purposes  of 
comparison,  to  polarize  starch-sugar,  the  solution  before  it  is  placed  in  the 
tube  of  the  sacchari meter  for  observation,  should  be  heated  for  five  minutes  to 
100°  to  get  rid  of  the  birotation,  and  obtain  at  once  the  lowest  reading. 


284  ANALYSIS  OF  COMMERCIAL  GLUCOSE. 

THE    DETECTION    OF    DEXTRIN    AND    STARCH-SUGAR   WHEN 
MIXED   WITH   RAW   AND   REFINED   SUGARS. 

I.  The  Adulteration  of  Haw  Sugar  with  Dextrin. 

—Commercial  dextrin  lias  been  added  to  raw  sugars  in 
order  to  give  them  a  higher  polarization,  and  consequently 
a  greater  market  value ;  .40  of  one  per  cent,  of  dextrin 
raises  the  saccharimetric  titre  about  one  per  cent.  Two 
qualitative  tests  are  commonly  resorted  to  for  detecting 
dextrin  under  these  conditions,  though  neither  is  entirely 
reliable  :  1.  Alcohol  of  95  per  cent,  added  to  a  concentrat- 
ed solution  of  sugar  containing  the  adulterant  gives  a 
white,  thread-like  coagulum,  while  more  dilute  solutions 
show  only  a  cloudiness  in  a  greater  or  less  degree.  The 
salts  present  in  raw  sugar,  and  particularly  sulphate  of 
lime,  give  a  similar  precipitate.  2.  A  solution  of  iodine  in 
iodide  of  potassium  produces  with  dextrin,  according  to 
the  method  of  manufacture,  a  wine  or  violet  red,  while 
some  varieties  do  not  give  any  coloration/-'  The  presence 
of  dextrin  may  be  detected  with  certainty  by  Chandler  and 
Rickett's  method  (page  287).  For  the  determination  of 
cane-sugar  the  process  of  inversion  and  estimation  with 
copper  liquor  will  have  to  be  resorted  to  (chap,  viii.)  f 

II.  Detection  of  Starch  Sugar  or  Syrup  when  mixed 
with  Raw  or  Refined  Sugars. — The  presence  of  these  sub- 

*  Boivin  and  Loiscau  (Wagner's  Jahresb.,  1870,  399)  give  the  following  as 
the  marks  of  sugars  containing  dextrin  :  1.  On  burning  they  give  off  the  odor  of 
heated  bread.  2.  They  are  very  difficult  to  filter,  and  the  filtrates  are  apt  to 
be  cloudy.  This  is  particularly  the  case  when  lead  solution  has  been  used  in 
clarifying.  3.  Owing  to  imperfect  mixture,  separate  lumps  of  dextrin  may  be 
separated  and  appropriately  tested. 

f  Lactose  or  milk-sugar  in  raw  sugar  may  be  detected  by  treating  the  latter 
with  twelve  times  its  weight  of  89  per  cent,  alcohol,  which  dissolves  the  sugar 
and  leaves  the  lactose. 


DETECTION  OF  GLUCOSE  IN  CANE-SUGARS.  285 

stances  may  in  general  be  shown  by  paying  attention  to  the 
following  points  :  1.  Sugars  mixed  with  powdered  or  granu- 
lated corn  glucose,  on  solution  in  water  invariably  leave 
white  particles  of  the  glucose  undissolved  ;  2.  Owing  to  the 
birotation  exhibited  by  solid  starch  and  corn  glucose,  it 
will  be  observed,  on  submitting  a  commercial  sugar  con- 
taining it  to  the  polariscopic  test,  that  the  reading  does  not 
remain  constant,  but  gradually  becomes  less  until  a  point 
is  reached  when  the  diminution  of  the  reading  ceases.  If 
the  solution  is  observed  immediately  after  it  is  prepared 
(without  heat),  as  little  as  three  to  five  per  cent,  of  starch- 
sugar  may  be  thus  detected.  This  test  only  applies  when 
the  sugar  is  mixed  with  solid  glucose,  as  the  syrup  does 
not  show  birotation.  3.  On  account  of  the  high  rotatory 
power  of  starch -sugar,  a  refined  sugar  mixed  with  it  will 
show  a  larger  percentage  of  cane-sugar  by  the  saccharime- 
ter  than  the  true  one  ;  hence  the  analysis  generally  adds  up 
over  one  hundred.  This  will  apply  whether  the  material 
used  for  mixing  is  solid*  glucose  or  the  syrup. 

With  these  three  tests  it  is  easy  to  determine  qualita- 
tively the  presence  of  starch  or  corn  glucose  in  any  sample 
of  sugar,  whether  raw  or  refined,  in  amounts  from  two  per 
cent,  upwards. 

There  exists  no  accurate  method  for  determining  the 
amount  of  commercial  glucose  in  any  refined  or  raw  sugar 
mixed  with  it.  The  glucose  itself  varies  greatly  in  compo- 
sition, and  the  invert-sugar  contained  in  raw  and  refined 
sugars  acts  toward  Fehling's  solution  precisely  as  does  the 
sugar  in  glucose.  The  ordinary  optical  method  cannot  be 
employed,  because  the  reading  of  the  saccharimeter  given 
by  a  mixture  of  cane  and  starch  sugars  is  a  resultant  of 
the  rotations  of  the  two  sugars,  together  with  that  of  the 


286  ANALYSIS  OF  COMMERCIAL  GLUCOSE. 

impurities  present  in  the  latter.  The  rotation  of  starch- 
sugars  from  different  sources  and  in  different  conditions, 
whether  solid  or  liquid,  varies  within  exceedingly  wide 
limits.  Clerget's  method  is  equally  inapplicable,  except  as 
a  qualitative  test,  for  the  reasons  stated  above.  The  un- 
suitableness  of  this  method  for  the  quantitative  estimation 
is  specially  prominent  on  account  of  the  optical  properties 
of  the  maltose,  dextrose,  dextrin,  and  soluble  starch  pre- 
sent, it  being  remembered  (page  136)  that  Clerget's  process 
is  intended  for  solutions  of  cane-sugar  containing  no  rota- 
tory substance  other  than  optically  active  invert-sugar  of 
known  specific  rotatory  power. 

Casamajor*  recommends  the  use  of  methylic  alcohol 
marking  50°  of  Gay  Lussac's  alcoholometer,  saturated  with 
starch-sugar,  as  a  qualitative  test  for  the  latter  when  mixed 
with  commercial  cane-sugars.  The  suspected  sugar,  after 
drying,  is  thoroughly  washed  with  the  test  solution,  which 
dissolves  the  cane-sugar  and  impurities,  leaving  the  glu- 
cose in  grains  and  powder.  It  seems  probable,  as  the  author 
suggests,  that  this  method  might  be  so  modified  as  to  give 
fairly  good  results  quantitatively,  perhaps  better  than  with 
the  very  unsatisfactory  methods  hitherto  proposed,  by  col- 
lecting the  undissolved  starch-sugar  on  a  weighed  filter, 
after  all  soluble  matters  have  been  removed  by  the  alco- 
holic sugar  solution,  and  the  strongest  methylic  alcohol 
(92J-0  Gay  Lussac),  applied  successively. 

Drs.  Chandler  and  Bicketts  f  have  devised  a  method  for 
estimating  the  right-rotating  substances  in  the  glucose 
added  to  a  commercial  sugar. 

*Jour.  Am.  Chem.  Soc.,  ii.  428.  }  Ibid.,  vol.  i. 


CHANDLER  AND  RICKETTS'S  METHOD.       fr-Vyr387 

V&*; 

This  consists  in  inverting  the  mixed  sugars  with  acids,  as 
in  Clerget's  process  (page  137),  and  observing  the  rotation 
in  a  water-bath  tube  at  92°  C.  (temperature  of  water-bath). 
Invert-sugar  at  87.2°  C.  has  no  effect  upon  the  polarized 
ray,  owing  to  the  fact  that  the  rotation  of  levulose  is  neu- 
tralized by  that  of  the  dextrose  which  is  constant  for  all 
temperatures  (see  invert-sugar,  page  89).  Hence,  when  a 
mixed  sugar  of  commerce  is  inverted,  the  cane-sugar  is 
'converted  into  invert-sugar,  which,  with  that  originally 
present,  is  optically  inactive  at  the  temperature  named. 
The  dextrose  and  other  bodies  from  the  starch-sugar  pre- 
serve their  specific  rotatory  effect.  When,  therefore,  a 
pure  commercial  sugar  is  inverted,  at  87.2°  the  rotation  is 
null,  while  if  any  corn  glucose  is  present  a  rotation  to  the 
right  will  be  shown,  and  in  proportion  to  the  amount  pre- 
sent. 

To  calculate  the  results  given  by  this  process  a  standard 
starch- sugar  was  taken  which  gave  "an  average  rotation  to 
the  right  at  92°  C.  of  87  divisions  of  the  saccharimeter 
scale  (Ventzke-Scheibler),  when  the  sample  tested  63  per 
cent,  by  Fehling's  method.  Hence,  if  26.048  grammes  be 

26.048  X  -6— 
the  amount  taken  for  observation,  — §7  x  100°°  =  !8.864 

grammes  is  the  amount  of  dry  substance  necessary  to  read 
100  divisions  on  the  scale,  or  each  division  is  equal  to  .1886 
gramme."  26.048  grammes  of  the  suspected  sugar  is  taken 
for  the  Ventzke-Scheibler  instrument,  inverted  with  hydro- 
chloric acid,  and  the  solution  observed  in  the  tube  heated 
to  92°  C.  Each  division  of  the  scale  read  corresponds  to 
.1886  gramme  reducing  substances,  as  shown  by  the  cop- 
per test,  added  to  the  sugar  under  examination,  in  the  form 


288 


ANALYSIS'OF  COMMERCIAL  GLUCOSE. 


of  corn  glucose  or  starch-sugar.     Figs.  39  and  39  a  show 

39- 


the  arrangement  adopted.     The  middle  portion  of  the  sac- 
charimeter  is  so  modified  as  to  admit  of  the  interposition 


CHANDLER  AND  RICKETTS'S  METHOD.  289 

of  a  water-bath  in  the  space  ordinarily  intended  for  the 
observation-tube  alone.  This  is  heated  from  below  by  two 
or  four  small  spirit-lamps,  and  an  opening  is  made  in  the 
cover  of  the  water-bath  for  a  thermometer  whereby  the 
temperature  of  the  water  is  regulated.  The  form  of  the 
tube  is  shown  in  Fig.  39  a,  which  is  merely  the  ordinary 

Fig.  39  «• 


one  provided  with  a  tubule  for  the  introduction  of  a  ther- 
mometer into  the  tube  itself. 

This  method  in  many  cases  is  capable  of  giving  useful 
results,  and  though  a  decided  advance  over  previous  meth- 
ods for  the  optical  estimation  of  sugar  in  the  presence  of 
starch-sugar,  yet  it  must  not  be  forgotten  that  when  the 
composition  of  the  adulterant  varies  considerably  from  the 
above  standard,  or  that  of  any  other  standard  taken,  the 
results,  considered  quantitatively,  will  be  misleading. 


CHAPTER   XV. 

ESTIMATION  OF  MILK-SUGAK. 

I.  By  Fehling's  Method. — Milk-sugar  reduces  the  al- 
kaline solution  of  oxide  of  copper  in  a  different  proportion 
from  dextrose  or  invert-sugar.     One  equivalent  of  milk- 
sugar  reduces  7.40  to  7.67  eq.  (Soxhlet  *),  7.40  to  7.44  eq. 
(Rodewald  and  Tollens  f).     10  c.c.  of  the  standard  copper 
liquor  is  equivalent  to  .067  gramme  sugar. 

Copper  X  .7635  J  =  milk 
Copper  oxide  X  .6096  j 

The  estimation  is  precisely  similar  to  that  made  for  dex- 
trose and  invert- sugar,  except  that  it  is  necessary  to  heat 
somewhat  longer,  as  the  reaction,  though  complete,  does 
not  take  place  so  rapidly  as  with  dextrose.  Either  the 
volumetric  or  gravimetric  methods  may  be  used. 

To  estimate  the  sugar  in  milk,  it  is  necessary  to  coagulate 
the  caseine  with  a  few  drops  of  hydrochloric  or  acetic  acids, 
and  filter,  before  proceeding  with  the  operation. 

II.  By  the  Optical  Method. — When  the  normal  weight 
of  32.680  grammes  for  the  Yentzke-Scheibler  saccharime- 
ter,  and  20.50  grammes  for  the  Soleil-Duboscq  and  other 
saccharimeters   in   which    the    normal   weight   is    16.19 
grammes  for  cane-sugar,  is  taken,  each  degree  of  the  scale, 
when  the  200  mm.  tube  is  used,  corresponds  to  one  per 

*  See  references  for  Soxhlet's  work,  pages  201,  203. 
\  Scheibler'8  Neue  Zeit.,  iv.  67-86. 
290 


ESTIMATION  OF  MILK-SUGAR  IN  MILK.  291 

cent,  milk-sugar.  As  milk-sugar  exhibits  the  phenomenon 
of  birotation,  it  is  necessary  to  heat  the  freshly-prepared 
solution  for  a  few  minutes  before  taking  the  reading  in  the 
saccharimeter. 

For  the  estimation  of  milk-sugar  in  milk,  the  fat  and 
caseine  must  be  first  removed,  the  latter  being  strongly 
levo-rotatory  ;  50  c.c.  of  the  milk  is  mixed  in  a  porcelain 
dish  with  25  c.c.  lead  solution  of  moderate  strength,  and 
the  mixture  heated  to  gentle  ebullition  and  allowed  to 
cool ;  it  is  then  washed  into  a  100  c.c.  flask,  which  is  filled 
to  the  mark,  and  the  solution  filtered.  The  clear  filtrate  is 
then  examined,  the  200  mm.  tube  being  used.  The  read- 
ings must  be  doubled  on  account  of  the  dilution  from  50 
c.c.  to  100  c.c.  If  the  milk  exhibits  an  acid  reaction  it 
must  be  neutralized  with  soda  solution  (Landolt). 


CHAPTER   XVI. 

Estimation  of  Dextrose  in  Diabetic  Urine. 

I.    BY  THE   OPTICAL  METHOD. 

FOE  ordinary  cases  the  mode  of  proceeding  is  exactly  as 
in  the  case  of  dilute  sugar  solutions  in  chapters  xi.  and 
xii.,  the  urine  being  decolorized  with  lead  and  bone-black 
when  necessary.  Owing  to  the  fact  that  the  specific  rota- 
tory power  of  dextrose  is  considerably  lower  than  that  of 
cane-sugar,  when  the  various  saccharimeters  are  employed 
the  normal  quantity  to  be  weighed,  in  order  that  the  read- 
ings may  indicate  percentages,  must  be  greater,  and  in  pro- 
portion to  the  relative  specific  rotations  of  the  two  sugars. 
Taking  [66.5]  D  for  cane-sugar,  and  [53]  D  for  dextrose,  we 
have  66.5  :  53  :  :  26.05  :  x  —  32.683  grammes,  which  is  the 
dextrose  normal  weight  for  the  Soleil-Scheibler  instrument. 
Calculating  similarly  for  the  others,  we  have,  when  the 
normal  quantity  for  the  saccharimeters  is  weighed  and 
made  to  100  c.c., 

1°  of  the  Laurent  and  Soleil-Duboscq  instruments  =  2.031 

grammes, 

1°  of    the    Soleil-Ventzke   instrument  =  3.268  grammes, 
1°  of  the  Wild  instrument  (sugar  scale)  —  1.255  grammes, 
1°  of  the  Mitscherlich  instrument  =  9.410  grammes, 

in  one  litre. 

Schmidt  and  Haensch  have  made  a  modification  of  the 
Soleil  instrument,  so  that  the  scale  reads  directly  the  num- 

292 


ESTIMATION  OF  DIABETIC  SUGAR.  293 

ber  of  grammes  dextrose  in  100  c.c. ;  this  is  called  the  dia- 
betometer. 

When  the  urine  contains  albumen  it  must  be  removed 
before  the  sugar  can  be  estimated,  as  the  former  body  has 
a  strong  rotation  to  the  left.  For  this  purpose  the  secre- 
tion is  heated  in  a  dish,  with  acetic  acid  added  to  acid  reac- 
tion, until  the  albumen  separates  in  flocks,  which  is  then  fil- 
tered off,  washed,  and  the  urine  with  the  washings  made 
up  to  the  initial  volume  ;  or  the  urine,  acidified  with  acetic 
acid,  may  be  diluted  with  a  concentrated  solution  of  so- 
dium sulphate  to  double  its  bulk,  when  the  albumen  sepa- 
rates and  may  be  filtered  off. 

Biliary  acids,  though  right-rotating,  are  seldom  present 
in  quantities  sufficient  to  affect  the  substantial  accuracy  of 
the  optical  method. 

When  the  urine  contains  less  than  2.00  grammes  of  sugar 
to  the  litre,  or  the  normal  secretion  is  to  be  tested,  the 
above  mode  of  proceeding  is  unsuitable.  Landolt  *  gives 
the  following  method  for  use  under  these  circumstances : 
To  one  or  two  litres  of  the  urine  neutral  acetate  of  lead  is 
added,  and  the  solution  filtered  ;  the  filtrate  is  mixed  with 
basic  lead  acetate  and  ammonia,  the  precipitate  formed 
containing  all  the  sugar  present.  This  precipitate  is  dif- 
fused in  alcohol  and  treated  with  sulphuretted  hydrogen 
gas,  the  lead  sulphide  filtered  off,  the  solution  decolorized, 
if  necessary  with  animal  charcoal,  evaporated  to  a  known 
volume,  and  tested  in  the  saccharimeter.  If  biliary  acids 
are  present  in  the  urine,  they  will  be  found  in  the  alcoholic 
solution,  and  invalidate  the  optical  test  to  some  extent.  To 
prove  whether  these  acids  are  present  or  not,  a  portion  of 

*  Das  optische  Drehungsvermogen,  p.  185. 


294         ESTIMATION  OF  DEXTROSE  IN  DIABETIC  URINE. 

the  alcoholic  solution  is  evaporated  to  dryness,  the  residue 
taken  up  with  water,  and  the  solution  obtained  allowed  to 
ferment  with  yeast  for  two  days,  or  until  the  sugar  is  de- 
stroyed. •  If  the  filtered  residual  solution  shows  a  right 
rotation,  biliary  acids  are  present,  and  a  correction  for 
them  must  be  made. 

n.  BY  FEELING'S  METHOD. 

The  Qualitative  Test.— "  Fifteen  or  twenty  drops  of 
the  urine  to  be  tested,  previously  decolorized  with  a  little 
powdered  bone-black  and  diluted  with  four  or  five  c.c.  of 
water,  are  treated  with  a  half  cubic  centimetre  of  sodium 
or  potassium  hydrate  solution,  and  then  a  very  dilute  solu- 
tion of  copper  sulphate  added  drop  by  drop.  Too  large  an 
amount  of  the  copper  salt  should  not  be  added,  as  in  that 
case  black  oxide  of  copper  separates  on  boiling,  obscuring 
the  red  color  of  the  cuprous  oxide  when  only  a  small 
quantity  of  sugar  is  present.  The  clear  blue  solution  is 
heated  nearly  to  ebullition,  without  shaking,  when  a  yel- 
low cloud  forms  on  the  surface,  followed  by  a  precipitation 
of  red  cuprous  oxide. 

1 '  A  second  mixture  prepared  in  the  same  way  is  allowed 
to  stand  quietly,  without  previous  heating,  from  six  to 
twenty-four  hours,  when,  if  sugar  is  present,  there  will  be 
a  precipitate  formed  in  this  case  also.  This  control  experi- 
ment is  of  great  importance,  and  ought  never  to  be  omit- 
ted, since  most  of  the  substances  which  reduce  copper  so- 
lution, like  sugar,  do  so  only  when  heated,  or  after  pro- 
longed boiling,  and  not,  like  diabetic  sugar,  in  the  cold" 
(Neubauer). 

The  Quantitative  Estimation.— This  determination  is 


ESTIMATION  OF  SUGAR  BY  COPPER  TEST.  295 

made  in  all  respects  according  to  the  ordinary  volumetric 
method,  or,  for  very  accurate  work,  after  the  modification 
of  Soxhlet.  See  chapter  viii.,  section  i.  The  gravimetric 
method  is  of  doubtful  accuracy,  on  account  of  the  possible 
precipitation  of  earthy  phosphates  or  other  salts,  under 
some  conditions.  It  is  best  to  decolorize  the  urine  with  a 
small  quantity  of  powdered  bone-black. 

If  albumen  is  present  it  must  be  separated  by  heating  to 
boiling  with  a  slight  excess  of  acetic  acid,  filtering,  and 
washing  the  precipitate. 

Uric  acid  is  probably  the  only  body  ordinarily  present  in 
urine  which  reduces  the  copper  solution.  According  to 
many  experiments  of  Neubauer,  the  uric  acid  in  normal 
and  diabetic  urine  has  no  appreciable  effect  on  the  results 
of  the  copper  test.  When  uric  acid  is  present  to  an  abnor- 
mal amount,  it  may  be  removed  by  treating  the  solution, 
previously  diluted  to  contain  %  per  cent,  sugar,  with  a  slight 
excess  of  basic  lead  acetate,  filtering,  adding  a  solution  of 
sulphurous  acid  until  all  lead  is  removed,  and  again  filter- 
ing. The  clear  lead-free  filtrate  may  be  used  for  the  sugar 
estimation. 


CHAPTER  XVII. 


THE  CHEMISTEY   OF  ANIMAL   CHAKCOAL. 

Bone-Black — Bone-Char — Animal  CJiar — Animal  Black — 
KriocTienkohle,  Or. — Charbo?i  d/Os,  Fr. 

Composition. — Animal  charcoal  is  the  carbonaceous 
residue  left  by  the  distillation  of  bones  in  close  vessels. 
Dr.  Wallace  gives  as  the  average  composition  of  a  good 
char: 

Carbon* 11.00 

Carbonate  of  lime 8.00 

Phosphates  of  lime  and  magnesia 80.00 

Alkaline  salts 40 

Sulphate  of  lime 20 

Oxide  of  iron. 10 

Silica 30 

100.00 

*  The  carbon  is  much  higher  than  that  of  the  bone-black  made  in  this 
country. 

The  following  analyses  give  a  good  idea  of  the  composi- 
tion of  American  chars  : 


i. 

2. 

3. 

4- 

5. 

6. 

7- 

8. 

a  -27 

2  56 

2.4S 

2.3Q 

2.78 

4.4-2 

2  O7 

i  76 

Carbon   

8  05 

767 

7  76 

7  ec 

8  17 

8  70 

8  47 

9  08 

6  71 

7  C.A 

8  76 

7.42 

7  60 

7  84 

608 

7  IQ 

Sulphate  of  lime.  . 
Iron  

trace. 

18 

.08 

qo 

trace. 

098 

trace. 

17 

1     , 

.06 

trace. 

O4 

trace, 
oc 

trace. 

jO 

Sand,  clay,  etc. 

43 

.32 

32 

.£7 

07 

Undetermined*  .  . 

81.26 

8L53 

80.602 

81.90 

80.71 

78.99 

83.33 

81.87 

Lbs.  percu.  ft.... 

IOO.OO 

42.7 

IOO.OO 

45.50 

100.00 

48.5 

100.00 

45.5 

100.00 

IOO.OO 

474 

IOO.OO 

IOO.OO 

These  analyses  represent  chars  of  the  best  quality,  in  grains  of  medium 
size. 

*  Alkaline  salts,  phosphates  of  lime  and  MgO,  etc. 

296 


ANALYSES  OP  CHAR. 


297 


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298  CHEMISTRY  OF  ANIMAL  CHARCOAL. 

Historical. — The  decolorizing  power  of  animal  char  was 
first  noticed  by  Lowitz,  but  Figuier  in  1811  proposed  its 
use  as  a  decolorizer.  In  1812  Derosne  introduced  it  into 
the  sugar  manufacture,  and  in  1821  Bussy  and  Payen 
thoroughly  investigated  its  properties  and  mode  of  action. 
It  was  first  used  for  sugar  solutions  on  the  large  scale  in  a 
state  of  fine  powder,  and  consequently  after  one  operation 
it  became  useless  for  another.  Dumont,  however,  in  1828, 
made  a  great  advance  in  the  practical  application  of  animal 
black,  by  employing  it  in  grains  and  filtering  the  sugar  so- 
lution through  a  column  of  it.  Afterwards,  the  char  was 
submitted  to  a  process  of  revivification  by  washing  and 
burning,  essentially  the  same  as  practised  at  the  present 
time. 

Mode  of  Action. — The  effects  of  animal  charcoal  on 
sugar  solutions  may  be  classed  under  two  heads,  though 
the  physical  action  is  the  same  in  either  case — viz.,  the 
removal  of  color,  and  tlie  absorption  of  other  soluble 
matters.  The  two  actions  seem  to  be  dependent  to  some 
extent,  and  the  color  of  the  filtered  solution  is  in  most 
cases  a  good  index  of  the  amount  of  purification  effected, 
though  not  always,  for  the  coloring  matter  in  sugar  so- 
lutions that  have  been  much  heated  is  entirely  removed 
with  great  difficulty,  while  the  absorption  of  salts  and 
other  matters  takes  place  in  a  normal  degree.  Filhol  gives 
a  table  showing  the  decolorizing  powers  of  various  sub- 
stances as  compared  with  bone-black  washed  with  hydro- 
chloric acid,  which  is  called  100 : 


NITROGEN  IN  CHAK. 


299 


Litmus. 

Red  Wine. 

Molasses. 

Cold. 

Hot. 

Cold. 

Hot. 

Cold. 

Hot. 

Hydrated  sesquioxide  of  iron.. 
"         oxide  of  lead  

128.9 

96.86 

54-54 

72.72 

7941 
25.96 
42.18 

5I-9I 
103-83 
46.15 

49-13 

52.24 
84.37 
25.96 
42.18 

Barium  sulphate  

Calcic  phosphate  or  carbonate.  . 
Magnesium  carbonate,  ,  

109 

90.28 

77 

IOO 

IOO 

IOO 

IOO 

IOO 

IOO 

The  absorptive  power  of  bone-black  is  owing  to  the  pre- 
sence of  carbon  in  a  minute  state  of  division.  The  phos- 
phate of  calcium  constitutes  a  framework,  as  it  were,  for  the 
carbon,  and,  after  the  calcination  of  the  bones,  remains  in 
a  very  porous  condition  ;  hence  the  lighter  the  char  for  a 
given  bulk  the  better  it  absorbs. 

Presence  of  Nitrogen.  —  The  carbon  contains  from  one 
to  one  and  a  half  per  cent,  of  nitrogen,  which  diminishes  to 
about  one-half  per  cent,  when  the  char  has  been  used  some 
time.  This  substance  seems  necessary  for  the  decolorizing 
effect,  as  no  vegetable  charcoal  destitute  of  nitrogen  has 
the  same  properties.  Mtrogenous  chars  prepared  in  dif- 
ferent ways  have  the  property  of  absorbing  color  in  va- 
rious degrees.  A  table  from  Muspratt  illustrates  this  : 

Decol.  Power. 


Ordinary  animal  black 

"  "  treated  with  hydrochloric  acid.. 

Ordinary  black  calcined  with  K2CO3 
Blood 


Albumen 

Gluten 

Oil 


1.6 

2o-° 
20.0 


chalk  ...................  ii.o 

phosphate  of  lime  .......  10.0 

K2CO3  ..................  15-5 

"      ..................  15-5 

phosphate  of  lime  .......  1.9 


Absorbing  Power  of  Char.— Brimmeyr's  experiments, 


300 


CHEMISTRY  OF  ANIMAL  CHARCOAL. 


confirmed  by  Schultz,  on  the  absorbing  power  of  animal 
charcoal,  gave  rise  to  the  following  conclusions:  1.  The 
absorptive  power  does  not  depend  on  the  mechanical  struc- 
ture, but  upon  the  amount  of  carbon  contained.  2.  Char 
which  has  lost  its  power  for  absorbing  one  substance  is 
capable  of  taking  up  another  body  of  a  different  chemical 
nature.  3.  The  quantities  of  matter  absorbed  by  bone-char 
of  various  kinds  are,  when  considered  in  relation  to  the 
amount  of  carbon  present,  really  equivalent,  and  probably 
independent  of  the  varying  chemical  nature  of  the  ab- 
sorbed substance.  4.  Bone-char  acts  the  quicker  and  better 
the  less  its  capillary  structure  has  been  altered  by  mechani- 
cal or  chemical  means. 

The  following  analyses,  taken  from  actual  work  in  a 
sugar  refinery,  show  the  absorptive  action  of  char  for  solu- 
ble impurities : 


Raw  Liquor. 

Filtered 
Liquor. 

Char 
Washings. 

Sugar  ... 

Q-3     CQ 

Qt     -5Q 

78.^0 

Grape-sugar  

2  14. 

2  2^ 

3.  2^ 

Organic  matter  not  sugar  

3.56 

„ 
2.OO* 

11.05 

Ash  

80 

.4^1 

7.22 

IOO.OO 

100.00 

IOO.OO 

*  43.82  per  cent,  absorbed. 


t  43.75  per  cent,  absorbed. 


Walkoff  *  gives  an  admirably  clear,  graphical  representa- 
tion of  the  progress  of  a  filtration,  showing  the  absorption 
of  alkalies  and  coloring  matter,  and  the  progressive  purifi- 
cation of  the  sugar  solution  (Fig.  40).  The  perpendicular 


Traite  Complet,  tome  ii.  191. 


ABSORPTIVE  POWER  OF  CHAR. 


301 


lines  show  the  hours  of  filtration,  and  the  others  the  rela- 
tive proportion  of  sugar  in  dry  substance,  alkalinity,  and 
decolorization  during  the  progress  of  the  operation. 
Absorption  of  Salts  and  Organic  Matters. — The 

soluble  substances  taken  up  by  char  are  either  organic  or 
mineral,  the  former  consisting  of  gums,  coloring  matter, 
albumen,  etc.,  and  the  latter  of  inorganic  bases  combined 
with  organic  or  mineral  acids.  The  organic  bodies,  nota- 
bly albumen,  are  retained  by  the  char  with  great  tenacity, 
so  that  long  washing  with  hot  water,  or  even  steaming, 

Fig.  40. 


/ 

Alkalinity 
M 

1,2 
1,1 
1,0 
0,9 

0,8 
0,7 
0,6 
0,5 
0,4 
0,3 
0,2 

P,i 

0,0 

j 

^  < 

Quotient 
of  Purity 
73 

79 
80 
81    Suj 

82 
88 
84 
85 
86 
87 
88 
89 
90 
91 
92 

1                      '                     1 

£\                            Haurs                            ? 
o  \                         ^^                        / 

Decoloration 

200 

225 
250 

275 

300     Decoloration 

325 
350 
375 
400 
425 
450 

475 
Alkafinity 
500 

525 
550 

ft    \l            2           3            4            5            6            7/      3\ 

TT 

/ 

i 

\ 

A 

i 

\ 

\v 

i 

i 

\\ 

/ 

/ 

i\ 

\  i 

/ 

i 

JS 

\ 

\| 

W 

\ 

\ 

/? 

/ 

\/7 

V 

/  / 

\ 

\l/ 

A 

\ 

\ 

X 

\ 

1 

\ 

i 

fails  to  remove  all  of  the  absorbed  material ;  some  inor- 
ganic salts  are  also  obstinately  retained.  The  soluble  mat- 
ters submitted  to  the  action  of  the  char  are  taken  up  in 
varying  amount,  depending  on  the  nature  of  the  body. 


302 


CHEMISTRY  OF  ANIMAL  CHARCOAL, 


Walkoff,*  working  with  weak  solutions  of  potash  and  soda 
salts,  arrives  at  the  following  results,  the  conditions  being 
the  same  in  all  experiments,  and  the  temperature  15°  C. : 


Per  cent, 
absorbed. 

Potassium  hydrate  (at  60°  C.). .  13.5 

41                "      (ati5°C.)..  16.6 

"          carbonate 25.0 

phosphate 30.7 

nitrate 6.5 

chloride 3*.o 

"       «... 1-3 

citrate 12.2 

"          sulphate 22.4 


Per  cent, 
absorbed. 

Sodium  carbonate 24. 

"  "        (at  60°  C.)..  18.3 

"        phosphate 32.3 

28.0 

"        nitrate 5.0 

"         sulphate 20.4 

Magnesium  sulphate 49.0 

Sodium  chloride. .  I. 


Bodenbenderf  has  also  examined  the  subject  and  ex- 
tended the  research  so  as  to  include  salts  of  organic  acids. 
In  the  table,  under  I.  are  included  dilute  solutions  of  the 
salts,  with  5  per  cent,  of  cane-sugar  added,  and  under  II. 
more  concentrated  solutions  without  sugar : 


Percent, 
absorbed. 

I. 

II. 

21.50 
16.50 
48.IO 
69.97 
4540 
48.20 
8.10 
9-!5 

28.70 

Sodium           "     

"       chloride  

13.51 
11-75 

The  absorbing  powers  of  char  for  different  alkaline  salts 
were  found  to  be  in  the  following  order,  commencing  with 
the  weakest :  Potassium  chloride,  sodium  chloride,  potas- 


*  TraitS  Complet,  tome  ii.  206. 


f  Slammer's  JaJiresb.,  x.  289. 


EEVIVIFICATION.  303 

slum  nitrate,  sodium  nitrate,  potassium  acetate,  sodium 
acetate,  potassium  sulphate,  sodium  sulphate,  magnesium 
sulphate,  potassium  carbonate,  sodium  carbonate,  and  so- 
dium phosphate. 

The  amount  of  purification  effected  by  char  in  a  sugar 
solution  is  directly  as  the  amount  of  tlie  former  used  to  a 
given  weight  of  sugar,  as  the  temperature,  and  as  the  time 
whicli  the  solution  is  in  contact  witJi  the  coal. 

Marks  of  a  Good  Char. — Good  animal  charcoal  has  a 
dull  black  color,  without  presenting  any  appearance  of  in- 
cipient fusion  on  the  surface,  and  does  not  contain  an 
undue  proportion  of  cellular  particles,  which  come  from 
small  and  inferior  bones,  and  have  by  no  means  the  deco- 
lorizing effect  of  the  char  made  from  the  large  bones.  It 
should  adhere  strongly  to  the  tongue,  and  not  contain 
much  fine  powder,  but  be  hard  and  tough  to  resist  the  great 
wear  to  which  it  is  subjected  during  filtration  and  revivifi- 
cation. The  size  is  regulated  by  the  density  and  tempera- 
ture of  the  liquor  to  be  filtered. 

Revivification. — After  bone-char  has  served  the  pur- 
poses of  filtration,  water  as  hot  as  possible  is  run  in  at  the 
top  of  the  filter,  which  displaces  in  part  the  sugar  solution 
remaining  in  contact  with  the  char,  and  at  the  same  time  it 
mixes  with  the  rest,  forming  a  dilute  solution  of  sugar  and 
the  impurities  taken  up  from  the  liquor  ;  this  dilute  solu- 
tion is  known  as  "  sweet  water."  By  the  action  of  the 
heated  water  the  char  gives  up  the  greater  portion  of  the 
absorbed  matter,  which  goes  in  part  to  the  sweet  water  and 
the  remainder  to  the  '  *  waste  water, ' '  which  is  the  wash- 
water  that  no  longer  contains  sufficient  sugar  to  make  it 
profitable  to  save.  The  "  sweet  water"  is  generally  boiled 
down  with  one  of  the  lower  products,  and  should  on  no  ac- 


304  CHEMISTRY  OF  ANIMAL  CHARCOAL. 

count  be  used  to  dissolve  comparatively  pure  raw  sugars 
for  refining. 

From  the  above  it  follows  that  the  purification  of  sugar 
solutions  by  bone-black  consists  in  removing  the  impuri- 
ties from  the  first  products,  but,  instead  of  eliminating 
them  entirely,  adding  a  large  portion  of  them  to  the  lower 
or  half-refined  products,  where  their  injurious  influence 
comes  less  into  play. 

The  second  step  in  the  revivification  consists  in  heating 
the  washed  char  in  closed  retorts,  out  of  contact  with  the 
air,  at  a  sufficiently  high'  temperature  to  perfectly  carbon- 
ize any  organic  matter  remaining  in  it,  and  to  bring  the 
char  back  to  the  physical  condition  in  which  its  absorbing 
properties  are  exerted  to  their  fullest  extent. 

Alteration  by  Use. — The  following  analyses,  taken 
from  actual  work,  show  the  progressive  changes  that  have 
taken  place  in  bone-black  used  in  a  refinery  where  raw  su- 
gars from  the  cane  were  worked : 


ANALYSES  OF  CHAR. 


305 


w"  . 

M 

0 

'.      °" 

rf 

M 

o 

CO 

M              .           M 

CO 

vn 

* 

00 

•      °. 

O 

M 

co 
CO 

CO            .             . 
O 

0 

o 

co" 

I 

'.    '  o 
'.      ° 

CO 

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CO 

CO          H 
CO          CO 

CO 

co 
vn 

s 

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8 

& 

CO 

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M 

5* 

CO 

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vn 

vn 

CO 

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CO 

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'*• 

CO 

in 

vn 
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M 

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;  ! 

M 

vn 

M 

CO              Tf 

CO          rj- 

vn 

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vn 

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:    * 

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?    ?     j 

M 

vn 

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in 

"3 

I         0 

<O 

CO 

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CO           O^            . 

CO 

vn 

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CO 

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vn 

M 

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Cl 

M 

3 

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co 
I       co" 

vO* 

co 

co          .          . 
vn         .          . 

vn 

in 

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vn 

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O        vn         . 

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co        vn 

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M 

Carbon  

Carbonate  of  lime.  .  .  . 

d 

0 

Insoluble  matter  
Sulphate  of  lime  
Sulphide  of  calcium..  . 

3* 
O 

en 

3 

Decolorizing  power  — 
of  color  absorbed  fr 

gar  solution  

30f>  CHEMISTRY  OF  ANIMAL  CHARCOAL. 

An  examination  of  the  table  shows  that  the  char  by  use 
undergoes  a  change,  which  will  be  examined  seriatim  in 
relation  to  the  various  constituents  of  the  black. 

Carbon  increases  owing  to  the  fact  that  some  organic 
matters  absorbed  are  held  with  great  tenacity,  and  no  prac- 
tical amount  of  washing  is  sufficient  to  remove  all  traces  of 
these  bodies.  The  consequence  is  that,  in  the  burning  in 
the  process  of  revivification,  the  residual  organic  matter  is 
carbonized  in  the  pores  of  the  coal,  and,  instead  of  increas- 
ing the  decolorizing  effect  of  the  coal,  the  opposite  is  the 
case,  as  a  quantity  of  inert  non-nitrogenous  carbon  is  de- 
posited in  the  body  of  the  grain,  making  it  more  dense  and 
decreasing  the  amount  of  cellular  surface.  A  large  per- 
centage of  carbon  in  a  new  char  is  often  a  mark  of  poor 
quality,  being  caused  by  imperfect  and  insufficient  burning 
of  the  bones.  As  a  rule  old  and  new  char  may  be  distin- 
guished by  the  proportion  of  carbon  contained. 

Carbonate  of  Lime. — The  tenor  of  this  salt  is  rapidly 
reduced  when  the  char  is  first  used  for  filtration,  and  then 
generally  remains  stationary  for  a  long  time  at  from  4.50 
per  cent,  to  3.50  per  cent.,  but  finally,  in  very  old  chars, 
the  percentage  may  be  lowered  to  less  than  the  last  figure  ; 
in  this  case  there  is  too  little  of  the  salt  for  normal  work- 
ing. Its  office  is  mainly  to  ensure  neutral  liquors  by  satu- 
rating any  free  acid  which  may  exist  in  the  solution,  or 
may  be  formed  by  the  lactic-acid  fermentation,  where  the 
temperature  of  filtration  is  too  low.  As  the  solutions  ought 
always,  whether  in  filtering  or  washing,  to  be  not  lower 
than  180°  F.,  there  can  be  no  danger  of  this  fermentation 
so  long  as  this  condition  is  complied  with.  By  taking 
proper  care  to  have  the  raw  liquor  sufficiently  limed, 
and  the  temperature  high  enough  in  the  filters,  the  amount 


SULPHATE  OF  LIME— IRON.  307 

of  carbonate  of  lime  in  the  char  will  remain  high  enough 
almost  indefinitely. 

In  the  beet-sugar  manufacture,  where  the  liquors  and 
juices  often  contain  a  large  excess  of  caustic  and  other 
lime-salts,  the  percentage  of  carbonate  is  apt  to  be  high 
rather  than  low.  It  has  in  that  case  to  be  removed  by 
treatment  with  hydrochloric  acid.  An  excess  of  the  car- 
bonate is  injurious  to  the  char  in  the  same  way  as  is  any 
other  insoluble  inert  body,  which  stops  up  the  pores  and 
reduces  the  available  filtering  surface.  Hard  water  con- 
taining much  carbonate  of  lime  is  not  suitable  for  washing 
char,  as  the  lime-salt  is  retained. 

Alkaline  Salts. — These  consist  largely  of  ammoniacal 
compounds,  and  are  only  found  in  considerable  quantity  in 
new  char.  If  suffered  to  remain  they  go  into  the  liquor 
and  act  injuriously  by  their  melassigenic  properties.  On 
this  account  new  char  should  be  thoroughly  washed  and 
burned  before  using. 

Sulphate  of  Lime. — This  salt  acts  by  filling  up  the 
pores  of  the  coal,  and  may  be  derived  from  the  sugar  treat- 
ed or  the  water  used  in  washing  the  char ;  it  is  strongly  re- 
tained by  the  char,  but  thorough  washing  is  the  remedy  in 
this  as  in  many  other  cases. 

Iron  is  a  highly  injurious  body,  and  is  derived  from  the 
sugar  treated  or  from  rusted,  insufficiently-painted  filters 
and  piping,  and  also  from  the  retorts  of  the  kilns  in  which 
the  black  is  burned.  When  existing  in  the  char  it  is  sure 
to  get  into  the  filtered  liquors,  and  especially  the  sweet 
waters,  more  particularly  when  they  are  a  little  acid.  It 
accumulates  in  the  yellow  sugars  or  lower  products  of  the 
refiner,  giving  them  an  undesirable  dull  grayish  cast  which 
greatly  lowers  their  marketable  value.  Such  sugars  also 


308  CHEMISTRY  OF  ANIMAL  CHARCOAL. 

darken  tea  to  which  they  are  added,  by  the  formation  of 
tannate  of  iron.  All  new  black  purchased  for  refining  pur- 
poses should  carry  very  low  percentages  of  iron. 

To  prevent  iron  from  getting  into  the  char  in  the  course 
of  manufacture,  the  filters  should  be  well  scraped  and  paint- 
ed as  often  as  is  necessary,  and  the  liquors  should  be  neu- 
tral. 

Insoluble  matter  which  resists  the  solvent  action  of 
strong  acids  on  the  char  consists  partly  of  quartz,  sand,  or 
clay — which  in  moderate  amount  is  not  objectionable — and 
also  of  hydrated  silica  derived  from  weak  sugar  solutions 
that  have  soured  and  precipitated  the  dissolved  silica. 
This  is  caught  in  the  char,  and  acts  in  the  manner  of  sul- 
phate of  lime  or  other  finely-divided  matters. 

Sulphide  of  calcium  is  apt  to  accumulate  in  char  that 
has  been  used  some  time  and  which  contains  much  sul- 
phate of  lime.  The  sulphate  is  reduced  in  contact  with 
the  organic  matter  or  carbon  in  the  reburning  of  the  char, 
forming  the  soluble  sulphide  which  goes  into  the  liquors. 
Sulphide  of  calcium,  coming  in  contact  with  the  iron  in  the 
liquors,  strikes  a  yellowish  green  color,  which  develops, 
even  after  the  solution  has  run  off  the  coal,  from  the  forma- 
tion of  ferrous  sulphide,  and  very  seriously  interferes  with 
the  operation  of  making  salable  sugars,  especially  for  the 
lower  products.  Calcium  sulphide  is  one  of  the  worst  im- 
purities that  can  exist  in  bone-black  used  for  purposes  of 
filtration,  and  any  sample  containing  more  than  a  very  small 
quantity  will  fail  to  give  a  satisfactory  working  on  the 
large  scale.  In  contact  with  an  acid  sugar  solution  sul- 
phide of  calcium  also  gives  off  hydrosulphuric  acid,  which 
at  favorable  temperatures  is  believed  to  predispose  the  su- 
gar solutions  to  fermentation.  In  the  series  of  analyses 


THE  EXHAUSTION  OF  CHAR.  309 

given  on  page  305,  the  last,  showing  .41  per  cent,  of  calcium 
sulphide,  represented  char  which  was  rejected  as  being  no 
longer  fit  for  filtration,  and  chiefly  owing  to  presence  of  the 
sulphide. 

Nitrogen  appears  to  greatly  aid  in  the  decolorizing  ac- 
tion of  the  carbon  in  animal  black,  and,  as  a  rule,  the 
higher  the  amount  the  better  the  char. 

It  is  often  a  question  submitted  to  the  chemist  as  to 
whether  a  given  char  is  so  far  exhausted  as  to  decolorizing 
properties  that  it  would  be  desirable  to  replace  it  with 
new.  Many  things  have  to  be  considered  in  this  relation, 
the  chemical  analysis  alone  not  always  being  a  sufficient 
guide,  as  chars  which  analyze  poorly  sometimes  decolorize 
very  well.  No  general  rule  can  be  laid  down  for  the  mat- 
ter, and  the  chemist  will  have  to  rely  largely  upon  the  re- 
sults obtained  in  working  on  the  large  scale  with  the  black 
in  question,  extending  over  a  sufficient  length  of  time,  and 
including  all  the  necessary  analytical  details ;  above  all, 
reliance  should  be  placed  on  his  general  experience  gained 
in  this  special  department. 

There  is  appended  a  series  of  analyses  of  bone-blacks,  L* 
showing  both  old  and  new  chars,  and  II.  f  char  of  English 
and  American  origin  that  has  been  used  in  filtration : 

*  Maumene,  Traite  Complet.  f  W.  Arnott,  Amer.  Chemist,  i.  216. 


310 


CHEMISTRY  OF  ANIMAL  CHARCOAL. 


I. 


Carbon..  ,      
Phosphaf?    f  lime- 
Carbonate  of  lime. 
Sulphate  of  lime..  . 
Sulphide  of  calcium 
Alkaline  salts  
Oxide  of  iron 

IO.2I 

76.94 

7.42 

.12 
.01 

.67 
02 

8.44 
80.31 

8-77 
.40 
.04 

•  35 
4-3 

9.88 

80.  1  1 

7.76 

.08 
.04 

17 

12.07 

76.35 
7.09 
.11 

•  33 

12 

10.65 

78.52 
7.21 

.20 
.08 

•17 
06 

24.22 

64-35 
4-82 
.84 
.14 
.12 

AT. 

26.12 
62.40 

3-35 
.88 
.16 
.24 
=6 

Sand  

•74 

I  71 

.02 

7Q 

.73 

I    35 

4  08 

Water  

4  o? 

.55 

I.O4 

1.  14 

2.38 

3  73 

2  21 

Real  density 

100.00 

2  80 

100.00 
2  928 

100.00 
2  QO^ 

100.00 

2  Q^7 

100.00 
o  QA'l 

100.00 
2  Q^Q 

IOO.OO 
2Q^7 

Apparent  density  : 
In  powder  

I  O7O 

006 

.044 

I.oSl 

.075 

I  144. 

I  388 

In  grain 

776 

804 

76o 

778 

771 

I  O88 

I    IQO 

Decolorizing    pow- 
er : 
In  powder  

142 

04 

116 

104 

165 

62 

ei 

In  grain 

Q-J 

71 

88 

6< 

IO2 

g 

II. 


4 

4 

% 

o 

o 

Q 

Q 

c 

J* 

o 

Origin. 

1 

1 

| 

1 

. 

% 

^ 

0 

o 

a 

[ 

^ 

* 

* 

Carbon      .......... 

12  90 

l6  35 

8.24 

II.  dO 

II  2O 

IO  2O 

IO  45 

Phosphates  

82.O4 

77.  Q3 

85.44 

87.48 

80.  6  1 

83  80 

83.43 

84.50 

Carbonates 

3  23 

3  3O 

3IO 

2  OO 

5  08 

3-50 

476 

q  71; 

Sulphates  

.27 

.20 

.42 

.Q2 

14 

.17 

.27 

Oxide  of  iron  

.51 

•33 

.48 

•  57 

•43 

.32 

•51 

•43 

Alkaline  salts  

.25 

.20 

.20 

.15 

.20 

.20 

.IO 

•  15 

Sand  etc  

.80 

1.  6O 

I  34 

.08 

.46 

I  OI 

Q_ 

45 

CHAPTER  XVIII. 

TJie  Analysis  of  Animal  Charcoal. 

ESTIMATION   OF  WATEE. 

DEY  for  two  hours  at  140°  C.     The  sample  should  not 
be  powdered. 

ESTIMATION    OF    CAEBON. 

Dissolve  four  or  five  grammes  of  the  finely -powdered 
char  in  about  35  c.c.  of  pure  hydrochloric  acid  diluted  with 
its  bulk  of  distilled  water ;  heat  on  a  water-bath  in  a  flask 
or  beaker-glass  for  half  an  hour,  with  frequent  agitation, 
until  the  soluble  part  has  all  been  taken  up.     Dilute  to 
about  200  c.c.  with  hot  distilled  water,  allow  to  settle,  and 
pour  on  a  filter  that  has  been  previously  washed  with  di- 
lute acid  dried  at  100°  and  weighed.     When 
the  liquid  has  all  filtered,  add  more  hot  water 
to  the  flask,  shake  well,  allow  to  subside,  and 
pour  off  the  clear  solution  from   the  unclis- 
solved  matter  ;  add  water  to  the  flask  a  third 
time,  with  a  little    hydrochloric    acid,   and 
transfer  the  carbon  to  the  filter  in  the  usual 
way.      Continue  the  washing  on  the  filter 
with  hot  water,  at  first  acidulated,  and  final- 
ly with  pure  water,  until  the  washings  have  no '  longer  an 
acid  reaction,  or  a  drop,  when  evaporated  on  platinum  foil, 
leaves  little  or  no  residue.     Dry  the  filter  at  100°  until  it 

311 


312  ANALYSIS  OF  ANIMAL  CHARCOAL. 

ceases  to  lose  weight,  the  weighing  being  performed  in  the 
same  vessel  (watch-glasses  or  a  weighing-flask,  Fig.  41)  in 
which  the  filter  had  been  previously  tared.  After  the 
last  weighing,  transfer  the  filter  with  the  carbon  to  a 
weighed  crucible,  burn  off  the  carbon,  and  reweigh.  The 
residue  in  the  crucible,  after  the  subtraction  of  the  fil- 
ter-ash, constitutes  the  insoluble  residue,  which,  taken 
from  the  last  weight  at  100°,  gives  the  amount  of  pure 
carbon. 

Example  : 

Amount  of  char  taken 4.500  grammes. 

Residue  +  weighing-flask  +  'filter  at  100°  .20.570        " 
Weighing-flask  -f  filter  at  100° 20;  150        " 


Carbon  -f  insoluble  matter 420 

Insoluble  matter ..  .019 


Carbon .401        " 

Crucible  after  ignition 15.140        " 

"  .15.120        " 


.020         " 
Filter-ash 001        " 

Insoluble  matter 019        " 

.401  X  100 

4  gQ —  =  8.91  per  cent,  carbon. 

•°19  *  10°  =.42  per  cent,  insoluble  matter. 

4.  OU 

Note. — Char  should  be  weighed  in  a  close  vessel  for  pur- 
poses of  analysis,  either  between  watch-glasses  or  in  a 
weighing-flask,  as,  according  to  the  state  of  the  atmosphere, 
or  the  amount  of  water  in  the  char  itself,  there  will  be  a 


SCHEIBLER'S  CALCIMETER. 


313 


gain  or  loss  during  the  time  necessary  to  take  an  accurate 

Fig,  42  * 


weight. 


ESTIMATION   OF   CARBONATE  OF  LIME. 

For  work  where  ordinary  accuracy  is  required,  this  esti- 
mation had  best  be  performed  according  to  Scheibler's 

*  The  author  is  indebted  to  Messrs.  Elmore  &  Richards,  of  New  York,  for 
the  above  engraving. 


314  ANALYSIS  OF  ANIMAL  CHARCOAL. 

process.*  The  results  for  low  percentages  are  accurate 
enough  for  all  technical  purposes.  We  give  Scheibler's 
description.  The  apparatus  is  represented  by  Fig.  42,  and 
consists  of  the  following  parts  : 

1.  The  evolution-flask  A,  in  which  the  assay  is  acted 
upon  by  hydrochloric  acid,  which  is  placed  in  the  rubber 
tube  S.  The  glass  stopper  of  A  is  perforated,  and  carries 
a  tube,  to  which  is  joined  a  rubber  tube,  r,  connecting  A 
with  B.  The  latter  has  a  gum  stopper  fitted  with  three 
glass  tubes ;  the  one  joined  to  r  extends  a  short  distance 
into  the  vessel,  and  has  fastened  to  it,  by  the  nack,  a  thin 
caoutchouc  bag,  K,  capable  of  being  easily  distended  by  a 
slight  pressure  ;  q  is  closed  by  a  pinchcock  while  the  estima- 
tion is  being  made,  and  serves  to  bring  B  into  communica- 
tion with  the  air  when  necessary.  The  glass  tube  u  also 
passes  through  the  stopper  of  B  and  connects  with 

(2)  The  graduated  tube  C,  which  is  divided  into  twenty- 
five  equal  parts  (about  4c.c.  each),  each  division  being  sub- 
divided into  tenths.     The  lower  end  of  this  is  in  communi- 
cation with 

(3)  The  straight  control-tube  D,  open  at  the  upper  end, 
and  at  the  lower  having  a  tube  of  smaller  calibre  passing  to 
the  bottom  of  the  two-necked  flask  E,  as  shown  in  the  fig- 
ure, the  connection  between  the  two  being  regulated  by  the 
pinchcock  p.      E  is  the  reservoir  for  the  water,  and  C  and 
D  are  filled  from  it  by  pressure  exerted  by  the  breath  of 
the  operator  through  0,  the  cock  p  preventing  the  reflux  of 
the  water.     C,  D,  and  u  are  fastened  to  an  upright  board 
by  suitable  means,  and  the  bottles  are  supported  on  a  shelf 
fastened  to  the  upright  board. 

*  Stammer's  Jahresb.,  1861-2,  244. 


SCHEIBLER'S  CALCIMETER,  315 

In  addition  to  the  apparatus,  the  following  requisites  are 
necessary  to  the  performance  of  the  test : 

1.  A  normal  weight  of  1.702  grammes. 

2.  A  centigrade  thermometer  graduated  from  12°  to  30°. 

3.  Diluted  hydrochloric  acid  of  specific  gravity  1.120. 

4.  A  solution  of  chloride  of  copper. 

5.  A  solution  of  ammonium  carbonate. 

For  the  execution  of  a  test  the  normal  quantity  of  pulver- 
ized char  (1.702  grammes)  is  placed  in  A,  which  must  be  dry, 
and  the  tube  S,  filled  with  acid  to  the  mark,  is  carefully 
placed  in  the  bottle.  E  is  then  filled  with  water,  and 
the  operator  forces  the  liquid  into  D  and  C  until  it  reaches 
a  little  above  the  zero-point  in  C,  when  it  is  allowed  to  flow 
out  by  opening  p  until  the  level  in  C  is  at  0.  Care  must 
be  taken  that  the  water  is  not  caused  to  overflow  into  B, 
for  in  that  case  the  apparatus  would  have  to  be  taken 
apart  and  dried.  The  stopper  being  now  placed  in  A,  a 
connection  with  B  is  made  by  the  tube  r.  If  the  level  of 
liquid  in  D  and  C  are  then  unequal,  the  equality  may  be 
restored  by  opening  the  cock  q  for  a  few  seconds,  and 
which  for  the  rest  of  the  operation  remains  closed. 

The  test  may  now  be  proceeded  with.  The  vessel  A  is 
held,  as  shown  in  the  cut,  so  that  the  acid  may  come  in  con- 
tact with  the  char,  and  the  bottle  gently  shaken  to  cause 
the  acid  to  thoroughly  mix  with  the  assay.  The  pressure 
of  the  gas  evolved  distends  the  rubber  bag  and  depresses 
the  column  of  water  in  C.  The  cock^?  is  now  opened  to  let 
the  water  in  B  flow  out,  the  operator  aiming  to  keep  the 
level  in  C  and  D  as  near  the  same  as  possible  during  the 
progress  of  the  determination.  When  all  the  gas  has  been 
given  off,  and  the  level  of  the  liquid  in  C  becomes  station- 
ary, p  is  closed  after  bringing  the  water  in  D  to  the  same 


3ic  ANALYSIS  OF  ANIMAL  CHARCOAL. 

level  as  that  in  C,  and  the  volume  and  temperature 
read  off. 

New  char  sometimes  contains  a  small  quantity  of  caustic 
lime.  When  this  is  the  case  the  finely-powdered  char 
before  being  tested  is  evaporated  on  the  water-bath,  after 
being  thoroughly  moistened  with  a  solution  of  carbonate 
of  ammonia. 

The  presence  of  sulphide  of  calcium  in  char  introduces  a 
slight  eiTor  in  this  method,  as  it  is  decomposed  in  contact 
with  the  acid,  setting  free  sulphuretted  hydrogen,  which 
would  be  reckoned  as  carbonic  acid  gas.  This  difficulty 
may  be  met  by  the  addition  of  a  small  quantity  of  cupric 
chloride  to  the  acid  used. 

The  apparatus  should  be  placed  in  a  position  where  the 
temperature  is  as  equable  as  possible.  The  estimation  is 
made  in  duplicate,  and  the  average  taken  as  the  true  result. 
The  following  table  gives  the  percentage  of  carbonate  of 
lime  from  the  volume  and  temperature  readings  : 


TABLE  FOR  SCHEIBLER'S  CALCIMETER. 


317 


IS 


•<  s 
§  « 

2  w 


o  w 


§, 


'ssaa 


S3 

i   N  Cl  C? 


HI  sag 


KSffa$K\sffla9Sj?8a; 

•  M  c4  «4^o  ^  ^o  d  a  ffs-a-^s  re  ?s  s  ?j  a1 


t-00  0>0  M 


0  M  CJ  CO^-Lr-UTO  t-j.00  0-0  M  Jj   CO 


'  M   N  CO  4  «TKO  t>«00  <3>  O  «  « 1  CO  4  £*D  t>.  t^.00  O-  O   «  ti   CO 


11  N  CO  Tf  IOO  t>^»  C^  O  H  M  CO  •*  >r*O  t^QO  CO  Ol  O  M 


8SSc? 


M  N  co4>^o  t^od  d>o  «  N  co4>AvD  jC.oo  cjo  o  «  N  co 


^2  £8  S3, 

o  M  r4  tj  jjj^  J^oo  <jg  M  cj  g  co 


IH  p  co  *  100  too  o^  o  M  p  co    -          tao  t>      « 


asac7ct 


^lo^  •TS'g 


M  c*  co  -^-irno  t>*oo  O^  O  •-« 


^saaffs 


f^»C»1<»'(»<»>(3NCO^cSiRtCt;i.So"vS 

•  H  ci  «4^ci  t^cd  *6  M  cj  co4^o  £00  .jo  M 


»ssas?a>!?fi&<8ff85aa'jr 


OO  -   N  CO"*""*0  t-^0   0>  0   w 


asas  ct 


M  C*  COrr^OOOC*  00  « 


0  «  CJ  CO^^vo  ^=0  S%  jj  J,  CO^- 


11  c<  co  Ttvo  t^oo  o*  o  HI  IH  N  co  -f  JJT«O  r-^»  o>  o  «  «  to  -t 


t^od  cji  o  M  N  cj  4  4  jog  too  c   o  «  N  to    - 


a  S  a  S  8*8  &*8  ^ 

«5  r^o  M  rj  jjj^g  J^»  o>  g  j^  jj  rj  to  j 


J8^S88'8;as«'8J?! 

'  w  N  4<rAO  t^oo  d\d  w  i 


«g§8  $3  &a  S-^^S  8  S  8  8  8  8  S  8  R  8  S  S  8  8  8 

'  M  «  4^vd  ^«5  d^O  «  PJ  cojjoo  rioo  o-o  «  gj  jog-jn 


318  ANALYSIS  OP  ANIMAL  CHARCOAL. 

An  example  will  show  the  use  of  the  ^able :  A  sample  of 
char  gave  a  volume  of  15.4  at  25°  C. 

15.0  volumes  =  14.27  at  25° 
.4        "       =      .37  at  25° 

14.64  per  cent,  calcium  carbonate. 

The  carbonate  of  lime  in  animal  black  may  be  estimated 
very  accurately  by  several  processes  depending  upon  the 
expulsion  of  the  gas,  determining  the  weight  lost,  and  cal- 
culating the  carbonate  of  lime  from  the  carbonic  acid  lost : 
C02  X  2.2727  =  carbonate  of  lime.  For  details  of  these 
and  other  methods  the  reader  must  be  referred  to  standard 
works  on  analytical  chemistry. 

Calculation  for  Removal  of  Carbonate  by  Acid. 
—In  the  beet-sugar  manufacture,  and  in  refining  where  the 
water  used  for  washing  the  char  is  very  hard,  calcic  carbo- 
nate accumulates  in  the  char  to  an  abnormal  extent,  and  it 
is  often  desirable  to  remove  the  excess  by  washing  with 
hydrochloric  acid.  Taking  7  per*  cent,  as  the  normal 
amount,  Scheibler  has  given  a  table  whereby  the  amount 
of  hydrochloric  acid  of  any  strength  required  to  reduce  the 
carbonate  to  the  prescribed  limit  may  be  calculated : 


TABLE. 


319 


S  &  Si 


vsv2£-s^<ss'8ss>c?s- 


*s  *s   &•  s-  s   a 


*o 


s>  2   a   s 

»    ^    fi    3 
E?   <S     8     SJ 


8    <S    -R 

uS      cs       1-1 

OO         tN.        t>, 


a  °  »   a 

CO      00       eg        g 


1>  i 


VO        00          M          IT) 


320  ANALYSIS  OF  ANIMAL  CHARCOAL. 

Example :  A  char  contains  12.30  per  cent,  calcic  car- 
bonate, and  the  acid  at  command  has  a  density  of  1.166,  or 
20°  B.  Now,  12.30  —  7.00  —  5.30  per  cent,  carbonate  to  be 
removed.  From  the  table  we  find — 

5.0  parts  CaC03  require  11.40  parts  acid, 
.3      "          "  "  .68  " 

12.08  parts,  of  sp.  gr.  1.166, 
or,  in  a  ton  of  2000  Ibs.  of  char, 

2000  X  12.08  per  cent.  =  241  Ibs.  of  commercial  acid  of  the 
indicated  strength. 

ESTIMATION   OF   CALCIC   SULPHATE. 

For  this  and  the  succeeding  determination  the  char 
should  be  very  finely  pulverized  and  passed  through  an  80- 
mesh  sieve.  Twenty  grammes  are  taken,  placed  in  a  porce- 
lain dish  on  a  water-bath,  moistened  with  distilled  water, 
•80  c.c.  of  pure  concentrated  hydrochloric  acid  added,  and 
the  whole  heated  for  an  hour  with  frequent  stirring.  At 
the  end  of  that  time  the  semi-fluid  mass  is  washed  into  a 
250-c.c.  flask,  diluted  to  the  mark,  and  the  mixture  filtered. 
To  200  c.c.  of  the  clear  filtrate,  corresponding  to  16  grammes 
of  the  original  substance,  is  added,  in  the  heat,  its  bulk  of 
water,  together  with  a  slight  excess  of  barium  chloride,  and 
allowed  to  stand  at  rest  from  six  to  twelve  hours.  The 
precipitated  barium  sulphate  is  now  filtered  from  the  clear 
solution,  and,  after  washing  two  or  three  times  with  boil- 
ing water  in  the  beaker,  is  treated  with  about  5  c.c.  of  a 
strongly  acid  solution  of  ammonium  acetate,  heated  for  five 
minutes,  diluted  with  boiling  water,  and  the  precipitate  and 
fluid  transferred  to  the  filter.  After  a  further  washing,  the 


ESTIMATION  OF  CALCIUM  SULPHIDE.  321 

filter  is  dried  and  the  weight  of  the  barium  sulphate  deter- 
mined in  the  usual  manner. 

Barium  sulphate  X  .58324  =  calcium  sulphate.* 


ESTIMATION   OF  CALCIUM   SULPHIDE. 

Twenty  grammes  of  the  finely-powdered  char  are  treated 
in  a  porcelain  dish  on  a  water-bath,  after  first  moistening 
with  water,  with  40  c.c.  of  fuming  nitric  acid  free  from 
sulphuric  acid,  added  in  small  portions  at  a  time  to  pre- 
vent too  violent  a  reaction.  The  mixture  is  heated,  with 
frequent  stirring,  for  half  an  hour,  when  40  c.c.  of  pure  con- 
centrated hydrochloric  acid  are  added  gradually,  and  the 
whole  kept  heated,  with  stirring  as  before,  for  twenty  min- 
utes longer.  The  contents  of  the  dish  are  now  transferred 
to  a  250-c.c.  flask,  and  when  cold  the  fluid  is  diluted  to  the 
mark  and  filtered  ;  200  c.c.  of  the  filtrate,  corresponding  to 
16  grammes  of  char,  after  dilution  with  an  equal  volume 
of  water,  are  treated  with  a  slight  excess  of  barium  chlo- 
ride, and  the  amount  of  sulphate  formed  determined  as  in 
the  estimation  of  calcium  sulphate. 

It  is  of  the  first  importance  that,  in  this  and  the  preced- 
ing estimation,  the  reagents  used  should  ~be  absolutely  free 
from  sulphur  in  any  form. 

For  the  calculation  of  the  results,  the  amount  of  the  ba- 
rium salt  found  in  the  determination  of  calcic  sulphate  is 
subtracted  from  that  as  obtained  above,  and  the  remainder 


*  The  error  owing  to  the  volume  occupied  by  the  undissolved  carbon  has 
been  experimentally  proved  to  be  without  sensible  effect  on  the  results,  and 
likewise  that  from  the  slight  solubility  of  barium  sulphate  in  a  liquid  contain- 
ing a  considerable  amount  of  free  hydrochloric  or  nitric  acids. 


322 


ANALYSIS  OF  ANIMAL  CHARCOAL. 


is  the  barium  sulphate  corresponding  to  the  calcic  sul- 
phide : 

Barium  sulphate  X  .3089  =  calcic  sulphide. 

Example:  10  grammes  of  char  containing  .50  per  cent, 
sulphate  of  lime,  when  treated  for  the  estimation  of  sul- 
phide, gives  .230  gramme  BaS04.  Now,  the  barium  sul- 
phate from  the  calcic  sulphate  would  be 

10.000  X  .0050  =  .050  gramme  CaS04,  and 
•05°    =  .0857  gramme  BaSO4. 


.58324 
.2300  —  .0857  =  .1443  gramme  BaSO4, 

furnished  by  the  oxidation  of  the  sulphide  ;  hence, 
/.1443  X  .3089^  x  100  =    44g  per  ^  Cag_ 

lies  and  Fahlberg's*  method,  though  more  tedious  in 
execution  than  the  above,  gives  very  good  results 

ESTIMATION   OF   CALCIC   PHOSPHATE. 

About  one  gramme  of  the  powdered  char  is  ignited  in  a 
crucible  until  the  carbon  is  burned  off ;  the  residue  is  then 
dissolved  in  50  c.c.  pure  nitric  acid,  and  the  solution  made 
up  with  water  to  100  c.c.  ;  25  c.c.  of  this  solution  is  taken 
and  treated  gravimetrically  by  precipitation  with  molyb- 
denum solution,  or  by  the  volumetric  method  with  ura- 
nium acetate.  For  details  of  these  methods  the  reader  is 
referred  to  Fresenius's  or  other  standard  works  on  analyti- 
cal chemistry. 


*  Ber.  Chem.  Q-eselL,  1879,  xi.  1187. 


ESTIMATION  OF  IRON.  323 

This  determination  is  rarely  necessary,  except  upon  the 
exhausted  char,  when  it  is  desired  to  estimate  its  value  for 
fertilizing  purposes. 

ESTIMATION   OF  THE  IKON. 

The  iron  may  be  determined  in  the  filtrate  from  the  car- 
bon, or  from  an  ignited  portion  of  the  char,  dissolved  in 
strong  hydrochloric  acid.  When  the  tenor  of  the  iron  is 
very  low  about  10  grammes  should  be  taken  for  the  assay. 
To  the  strongly  acid  solution,  platinum  foil  and  a  piece  of 
iron-free  zinc  are  added  to  reduce  the  sesquioxide  to  protox- 
ide. When  the  liquid  no  longer  gives  a  red  coloration  with 
a  drop  of  ammonic  sulphocyanate  solution,  the  reduction  is 
complete.  The  iron  in  the  ferrous  condition  is  then  deter- 
mined by  a  standard  solution  of  potassium  permanganate. 

Preparation  of  the  Standard  Solution.— This  solu- 
tion is  prepared  by  dissolving  about  2J-  grammes  of  the 
crystallized  salt  in  water  and  diluting  to  one  litre.  To  find 
the  exact  amount  of  iron  that  the  solution  is  equivalent  to, 
1.500  grammes  pure  crystallized  oxalate  of  ammonia  are  dis- 
solved in  water,  and  the  solution  made  to  250  c.c.;  50  c.c. 
of  this  are  taken,  diluted  with  the  same  bulk  of  water, 
about  5  c.c.  of  pure  concentrated  sulphuric  acid  added,  and, 
after  warming  to  60°,  the  permanganate  solution  from  a 
burette  is  run  in.  At  first  the  color  does  not  disappear 
rapidly,  but  this  soon  alters,  and  as  the  liquid  to  be  stan- 
dardized is  dropped  in  the  color  becomes  instantly  dis- 
charged as  long  as  any  of  the  salt  remains  unoxidized. 
As  soon  as  the  color  becomes  permanent,  and  the  solution 
is  of  a  very  faint  rose-color,  the  end  point  of  the  reaction 
is  attained  ;  71  parts  of  ammonic  oxalate  are  equivalent  to 
56  parts  of  iron. 


324  ANALYSIS  OF  ANIMAL  CHARCOAL. 

Example:  1.620  grammes  oxalate  of  ammonia  was  dis- 
solved to  250  c.c.,  and  50  c.c.,  equal  to  .340  gramme  of  the 
salt,  taken  for  the  titration,  which  required  42  c.c.  of  the 
permanganate.  Hence  42  c.c.  is  equivalent  to  .340  gramme 
oxalate,  or 

71  :  56  : :  .340  :  x  =  .2682. 

2689 
•—- —  =  .006385  gramme  iron  for  1  cubic  centimeter  of  the 

standard  solution.     The  standardizing  should  be  done  in 
duplicate. 

Pure  metallic  iron  in  the  form  of  pianoforte-wire  may  be 
used  in  the  place  of  the  ammonic  oxalate,  by  the  solution 
of  a  weighed  portion  of  it  in  pure  sulphuric  acid  in  an  at- 
mosphere of  carbonic  acid  or  steam  to  prevent  oxidation/" 

ESTIMATION   OF   SOLUBLE   MATTEE. 

To  25  grammes  of  the  finely-powdered  char  are  added 
200  c.c.  of  warm  water  (not  above  65°),  and  the  mixture 
allowed  to  stand  for  a  half-hour,  with  frequent  agitation. 
The  insoluble  matter  is  allowed  to  settle,  the  clear  liquid 
poured  off  through  a  filter,  and  about  100  c.c.  more  of  wa- 
ter added  to  the  residue,  which  is  treated  as  before,  but  for 
a  shorter  time,  and,  after  settling,  the  supernatant  liquid  is 
filtered.  The  washing  is  repeated  once  more,  the  undis- 
solved  residue,  together  with  the  liquid,  is  transferred  to 
the  filter,  and  the  insoluble  matter  remaining  on  it  is 
washed  until  free  from  anything  soluble.  The  combined 

*  Chlorine  is  set  free  when  permanganate  is  added  to  a  solution  containing  ' 
hydrochloric  acid,  which  tends  to  introduce  an  error  in  the  results  of  iron  de- 
terminations made  under  such  conditions.    For  the  small  amounts  of  iron  in 
bone-char,  however,  the  influence  of  this  error  in  the  above  estimation  may  be 
altogether  neglected.    (See  Fresenius'  Quant.  Analysis,  Am.  ed.,  198.) 


ESTIMATION  OF  SOLUBLE  MATTER.  325 

filtrates  are  evaporated  in  a  platinum  dish  over  a  water- 
bath  to  dryness,  with  the  addition  of  sufficient  hydrochlo- 
ric acid  to  give  the  solution  a  faint  acid  reaction,  in  order 
to  prevent  the  escape  of  ammonia  as  carbonate  and  sul- 
phide. The  addition  of  the  acid  alters  the  combination  of 
some  of  the  bodies  present,  but  the  error  introduced  is 
slight. 

The  weight  of  the  dried  residue  is  the  total  soluble  mat- 
ter. After  the  last  weighing  the  dish  is  ignited  only  for  a 
time  sufficient  to  burn  off  the  carbon,  and  the  inorganic  re- 
sidue constitutes  the  soluble  mineral  matter,  while  the  dif- 
ference between  this  and  the  total  is  the  organic  soluble 
matter. 

W.  Thorn  *  determines  the  organic  matter  in  char  by 
taking  50  grammes,  heating  with  25  c.c.  soda-lye  of  1.4  sp. 
gr.  and  200  c.c.  of  water,  and  washing  out  the  yellow  solu- 
tion with  hot  water.  The  alkaline  solution  obtained  is  su- 
persaturated with  sulphuric  acid  and  titred  with  solution 
of  potassium  permanganate ;  5  parts  of  organic  matter  = 
1  part  of  salt,  or  1  c.c.  of  normal  permanganate  solution  = 
.158  gramme  organic  matter.  This  process  may  give  good 
comparative  results. 

ESTIMATION  OF   STTGAE. 

One  hundred  grammes  of  powdered  char  are  heated  with 
two  or  three  times  its  weight  of  hot  water  for  a  half -hour, 
with  occasional  shaking ;  the  clear  solution,  after  settling, 
is  filtered  and  the  washing  repeated  twice  ;  and  finally  the 
residue  is  brought  on  the  filter  and  further  washed  until  all 
soluble  matter  is  removed.  The  filtrates  are  evaporated  on 

*  Wagner's  Jahresb.,  1875,  812. 


326  ANALYSIS  OF  ANIMAL  CHARCOAL. 

a  water- bath,  in  a  porcelain  dish,  to  about  80  c.c.,  caustic 
alkali  being  added  to  very  slight  alkaline  reaction.  The 
solution,  after  cooling,  is  made  up  to  100  c.c.,  and  polarized 
after  the  free  alkali  has  been  saturated  by  acetic  acid.  If 
the  amount  of  sugar  is  too  small  for  the  saccharimetric  test, 
resort  must  be  had  to  the  inversion  method,  which  is  more 
accurate  in  this  case  and  should  be  generally  preferred. 
When  this  method  is  used  the  liquid  may  be  evaporated 
with  the  addition  of  hydrochloric  acid  to  invert  the  sugar, 
and  the  invert-sugar  formed  estimated  by  Fehling's  me- 
thod, either  gravimetrically  or  volumetrically.  When  the 
char  is  properly  washed  the  amount  of  sugar  remaining  in 
it  is  extremely  small,  and  cannot  be  estimated  by  the  po- 
larimetric  method. 

ESTIMATION   OF  SPECIFIC   GRAVITY. 

1.  Apparent  Specific  Gravity.— This  is  simply  a  com- 
parison of  the  weight  of  equal  volumes  of  water  and  char. 
The  determination  is  made  by  filling  a  tared  half -litre  flask 
with  char,  accompanied  with  a  gentle  shaking,  and  taking 
the  weight,  which,  after  subtracting  that  of  the  flask,  gives 
that  of  the  half -litre  of  char.  This  divided  by  the  weight 
of  the  same  volume  of  water  gives  the  apparent  specific 
gravity. 

This  determination  is  of  little  use  in  estimating  the 
value  of  char,  unless  the  size  of  the  grains  in  each  sample 
compared  is  the  same,  and  also  that  all  conditions  of  the 
experiments  are  similar,  such  as  the  amount  of  shaking, 
etc.  The  apparent  specific  gravity  is  often  expressed  in 
another  form  as  the  weight  of  one  cubic  foot  of  the  mate- 
rial ;  it  may  be  calculated  by  the  formula— 


SPECIFIC  GEAVITY.  327 


P 


_  W  X  28.315 
453.6       ' 


in  which  P  equals  the  avoirdupois  pounds  in  one  cubic  foot, 
and  W  the  weight  in  grammes  of  one  litre. 
2..  Absolute    or    Real    Specific    Gravity.— Place  50 

grammes  of  the  char  in  a  tared  100-c.c.  flask  partially 
filled  with  distilled  water,  boil  for  some  minutes  to  free 
from  air,  fill  to  100  c.c.  after  cooling,  and  weigh.  The  cal- 
culation is  illustrated  by  an  example : 

Char  +  flask  +  water 180  grammes. 

Char  (50  grammes),  flask  (55  grammes).     105 

Water 75 

As  the  flask  without  char  would  hold  100  grammes  of 
water,  25  grammes  must  have  been  displaced  by  char ; 
hence 

5?  =  2.000  sp.  gr. 

The  sp.  gr.  thus  obtained  is  independent  of  the  pores  in 
the  coal,  and  hence  the  greater  the  density,  other  things 
being  equal,  the  poorer  the  quality  of  the  char. 

ESTIMATION   OF  THE  ABSOEPTIVE  POWER. 

I.  The  Absorptive  Power  for  Color  and  Soluble 
Matter  determined  on  the  Large  Scale  (by  Stam- 
mer's colorimeter,  Fig.  33). 

For  this  purpose  the  sugar  solution  is  compared  before 
and  after  filtration.  The  color  of  the  liquors  referred  to  the 
sugar  present,  is  determined  according  to  directions  given 


328 


ANALYSIS  OF  ANIMAL  CHARCOAL. 


in  chap.  ix.  ;  the  difference  in  the  solutions,  before  and  after 
filtration  represents  the  color  absorbed.  The  amount  of 
organic  matter  and  salts  taken  up  is  also  determined.  It- 
is  essential,  in  order  that  these  results  should  be  of  any 
value,  that  an  average  sample  of  each  liquor  should  be  ope- 
rated upon,  and  it  should  be  especially  assured  that  no 
" sweet  water"  or  syrup  foreign  to  the  liquors  under  ex- 
amination be  allowed  to  mix  with  them.  The  following  is 
an  example  taken  from  actual  working : 


Liquor. 

Per  cent,  ab- 
sorbed. 

Before  filtration. 

After  filtration. 

88.40 
5.23 
541 
.96 

91.30 
5.67 

2.38 
.65 

56.0 
32.3 

57-4 

Organic  matter  not  sugar  

Ash  

Color  referred  to  per  cent,  of  sugar. 

IOO.OO 

54 

100.00 

23 

An  estimation  made  as  the  above,  if  from  correct  samples, 
is  of  great  value  in  forming  an  opinion  as  to  the  condition 
of  the  char  in  actual  use,  and  should  never  be  neglected 
where  it  is  practicable  to  make  it. 

II.  Estimation  of  the  Decolorizing  Power  in  the 
Laboratory.— This  method  has  to  be  resorted  to  in  the 
examination  of  char  for  purchase,  or  when  a  comparatively 
small  sample  is  at  the  disposal  of  the  operator.  Dilute  any 
sample  of  dark-colored  molasses  or  syrup  with  five  times 
its  weight  of  water,  and  determine  the  color  of  the  solution 
by  the  colorimeter.  Next  weigh  100  grammes  of  the  coal 
to  be  examined,  place  it  in  a  flask  with  300  c.c.  of  the  dilute 


DECOLORIZING  POWER.  329 

sugar-liquor,  heat  on  a  water-bath  to  100°  for  one  hour, 
shaking  at  intervals,  filter,  allow  to  cool,  make  up  any 
loss  by  evaporation  by  adding  water,  and  observe  the  color 
again.  The  difference  before  and  after  this  treatment  re- 
presents the  decolorizing  power  of  the  char.  Example  : 

Before  filtration 28 

After          "  18 


10 

—  —  35.70  per  cent,  of  the  original  color  absorbed. 

28 

It  is  important  that  the  conditions  in  all  respects  should 
be  the  same,  in  this  determination,  when  made  at  different 
times  and  on  different  samples.  A  well-defined  method  of 
procedure  should  be  laid  down,  not  to  be  varied  from  in  any 
case,  as— the  char  should  always  be  used  of  one  degree  of 
fineness,  and  the  sieve  used  to  bring  it  to  that  if  necessary  ; 
the  dilution  and  composition  of  the  sugar-liquor  should  be 
as  nearly  as  possible  the  same,  as  well  as  the  proportion  by- 
weight  of  char  to  volume  of  liquor  employed,  degree  of 
heat,  time  of  the  experiment,  amount  of  shaking,  etc. 

ESTIMATION   OF  THE  COLOR  WITH  DUBOSCQ'S  COLORIMETER. 

A  A'  are  two  glass  cylinders  with  plane  bottoms  (Figure 
43),  one  of  which  is  destined  to  receive  the  solution  to  be 
examined,  and  the  other  the  standard  liquor.  Two  tubes, 
B  B',  of  small  diameter,  closed  at  the  lower  ends  by  glass 
plates,  and  capable  of  upward  and  downward  motion  by 
means  of  a  rack  and  pinion,  are  placed  behind  the  instrument 
on  the  upright  support.  Each  pinion  has  a  pointer,  which 
measures  upon  the  divided  scale  the  respective  distances 


330 


ANALYSIS  OF  ANIMAL  CHARCOAL. 


between  the  bottoms  A  A'  and  B  B'.  The  upper  part  of 
the  instrument  carries  a  system  of  prisms  and  a  small  tele- 
scope, D,  which  enables  the  operator  to  see  the  relative  color 
of  the  solutions  under  examination  after  the  manner  of 
Stammer's  colorimeter.  A  movable  mirror  placed  at  E 
throws  the  light  through  the  solutions.  In  the  form  of  the 

F'g-  43- 


apparatus  shown  the  light  reflected  from  E  had  a  tendency 
to  enter  the  tubes  out  of  the  exact  centre.  To  remedy  this 
Duboscq  has  lately  made  an  improvement  which  consists 


DUBOSCQ'S  COLORIMETER.  331 

in  interposing  between  the  mirror  and  the  bottom  of  the 
tubes  a  system  of  two  birefrigerent  prisms,  joined  together 
at  their  bases  so  that  the  line  of  contact  is  exactly  between 
A  A'  extended. 

The  type-liquor  is  made  by  dissolving  two  grammes  of 
caramel  in  water  and  diluting  the  solution  to  one  litre. 
The  caramel  is  prepared  by  heating  refined  sugar  for  one 
and  a  half  hours  on  a  paraffin-bath  at  a  temperature  not 
above  215°.  A  little  of  the  mass  should  be  taken  out  at 
the  end  of  that  time,  inverted  by  heating  with  acid,  and 
tested  with  copper- liquor  for  sugar  ;  if  any  is  present  the 
heating  must  be  continued  until  all  the  sugar  has  been  de- 
composed. The  caramel  should  be  preserved  in  a  tight 
bottle. 

The  use  of  Duboscq's  colorimeter  is  as  follows:  Of  raw 
sugar  or  syrup  a  known  weight  is  dissolved  in  water,  and 
the  solution  made  to  100  c.c.  and  observed  in  the  instru- 
ment. At  the  commencement  of  the  experiment  B  B' 
should  stand  at  the  same  height,  A'  being  filled  with  the 
type -liquor  and  A  with  the  sugar  solution  to  be  examined. 
If  the  colors  of  the  luminous  field  of  the  apparatus  appeal- 
unequal  on  either  side  of  the  vertical  line,  A  is  elevated  or 
depressed  by  its  appropriate  pinion  until  equality  of  tint  is 
obtained.  The  relative  heights  of  the  two  columns  of  col- 
ored solution  is  measured  in  millimetres  on  the  back  of  the 
instrument.  The  proportion  of  caramel  or  coloring  matter 
is  in  inverse  ratio  to  the  heights  of  the  liquid  columns. 
Thus  the  standard  caramel  solution  contains  in  100  c.c. 
.200  gramme  caramel,  from  which  datum  the  percentage  of 
coloring  matter  in  a  sugar  solution  of  known  strength  may 
be  readily  calculated.  Example  :  The  heights  of  the  liquid 
columns  as  measured  on  the  scale  are  20  mm.  for  the  stan- 


332  ANALYSIS  OF  ANIMAL  CHARCOAL. 

dard  and  40  mm.  for  the  solution  to  be  compared  ;  then,  as 
100  c.c.  of  the  former  contain  .200  gramme  caramel,  we  have 

20  :  40  :  :  x  :  .200  =  .100  gramme 

coloring  matter  in  100  c.c.  of  the  solution  tested,  which 
divided  by  the  amount  of  the  original  substance  in  100  c.c. 
gives  the  percentage. 

To  test  the  decolorizing  power  of  char  by  Du- 
boscq's  Method,  a  weighed  portion  of  the  char  is  mixed 
with  a  known  volume  of  the  type-liquor  and  heated  for  a 
half  or  one  hour,  with  the  precautions  as  to  the  relative 
conditions  of  experiments  mentioned  on  page  329.  The 
difference  in  color  before  and  after  decolorizing  shows,  by 
a  calculation  similar  to  the  one  above,  the  actual  amount 
of  caramel  removed. 

Duboscq's  process  maybe  used  with  Stammer's  instru- 
ment, and,  in  as  far  as  it  relates  to  the  decolorizing  power 
of  char,  Duboscq's  is  theoretically  a  better  method  than 
Stammer's,  because  the  type-liquor  is  of  supposed  constant 
composition  in  the  former,  thus  approaching  an  absolute 
standard,  while  with  the  latter  a  solution  of  constant  color 
or  composition  cannot  always  be  had.  Unfortunately  for 
the  accuracy  of  Duboscq's  process,  it  is  practically  exceed- 
ingly difficult,  if  not  impossible,  to  prepare  the  standard 
caramel  solution  at  different  times  having  exactly  the  same 
tinctorial  power.  This  fault  in  the  method  does  not,  how- 
ever, affect  the  general  usefulness  of  the  colorimeter  as  a 
measurer  of  color  in  sugar  solutions. 

COEENWINDEE'S  METHOD  FOE  ESTIMATING  THE  ABSOEBING 
POWEE  OF  CHAE  BY  A  SOLUTION  OF  CALCIC  SUCEATE. 

To  prepare  the  su crate  solution,  dissolve  125  grammes  of 


THE  POTASH  TEST.  333 

sugar  in  600  to  800  c.c.  of  water,  add  15  to  20  grammes 
caustic  lime,  boil  five  minutes,  allow  to  cool,  and  make  to 
one  litre.  To  100  c.c.  of  this  solution  50  grammes  of  the 
char  to  be  examined  are  added,  and  the  whole  left  to  stand 
for  an  hour,  with  frequent  agitation,  and  then  filtered. 
When  the  operation  is  finished,  a  part  of  the  lime  salt  is 
absorbed',  and  this  is  to  be  estimated.  By  determining  the 
amount  of  lime  by  standard  nitric  acid  in  50  c.c.  before  and 
after  the  action  of  the  char,  the  desired  result  is  obtained. 
(See  estimation  of  alkalinity,  page  258.) 


TEST  TO  DETERMINE  THE  COMPLETENESS  OF  ttVA&IIING  AND 

BURNING. 

g*M 

This  is  by  boiling  for  a  few  moments  small  portions  of 
the  char  with  solutions  of  sodium  or  potassium  hydrate  of 
20°  B.  A  yellow  or  brown  color  shows  the  presence  of  or- 
ganic matter,  and  the  greater  the  amount  the  greater  the 
intensity  of  the  color.  The  char,  if  properly  burned,  will 
give  no  reaction  by  this  test,  while  the  simply  washed  but 
unburned  article  should  not  give  more  than  a  lemon-color 
for  ordinarily  good  syrups  filtered,  or  *a  somewhat  darker 
color  for  lower  products. 

One  circumstance  may  render  the  indications  of  the  above 
test  fallacious — that  is,  when  iron  and  sulphide  of  calcium 
are  present  in  the  char  to  a  considerable  extent,  as  often 
happens  in  old  chars,  they  act  upon  each  other  in  the  pre- 
sence of  caustic  alkali,  producing  a  yellowish  or  greenish 
tint  in  the  solution,  due  to  the  formation  of  ferrous  sul- 
phide. This  indication  may  be  distinguished  from  that  of 
the  simple  action  of  alkali  on  organic  matter  by  the  ten- 
dency of  the  solution  in  the  former  case  to  acquire  a  tint 


334  ANALYSIS  OF  ANIMAL  CHARCOAL. 

of  green  on  standing,  and  by  the  fact  that  the  reaction 
readily  takes  place  in  the  cold.  Char  capable  of  giving  a 
decided  green  color  under  the  above  circumstances  gene- 
rally carries  a  high  percentage  of  the  sulphide,  and  is  en- 
tirely unfit  for  the  best  uses  (page  308). 


APPENDIX. 


NOTE 

CONCERNING  THE  ACTION  OF  THE  ORGANIC  MATTER  NOT 
SUGAR  OCCURRING  IN  CANE  AND  BEET  PRODUCTS,  ON 
ALKALINE  SOLUTION  OF  COPPER  OXIDE. 

It  lias  been  asserted  that  the  organic  matters  present  in 
impure  commercial  sugars  and  syrups  have  a  considerable 
reductive  effect  on  the  copper  solution  employed  in  Fehl- 
ing'  s  method  and  its  various  modifications  for  the  estima- 
tion of  invert-sugar.  To  avoid  this  supposed  source  of 
error,  it  has  accordingly  been  recommended  that  sugar 
solution  before  testing,  should  be  treated  with  excess  of 
basic  lead  acetate,  filtered,  the  metallic  salt  remaining  in 
solution  precipitated  with  sulphurous  acid,  and  the  result- 
ing liquid  after  filtering  again,  used  for  the  sugar  deter- 
mination. 

In  order  to  prove  whether  the  organic  matters  acted 
as  asserted  with  Fehling's  solution,  the  author  has 
made  some  experiments  on  the  most  impure  saccharine 
material  obtainable  from  a  variety  of  sources.  The 
manner  of  conducting  the  experiments  was  as  follows: 
The  hot  solution  of  the  substance  operated  upon  was 
treated  with  excess  of  basic  lead  acetate  and  the  pre- 
cipitate washed  thoroughly  with  a  large  excess  of  hot 
water.  To  be  assured  that  no  sugar  should  remain  in  the 

835 


336  APPENDIX. 

precipitate  as  lead  sucrate,  the  washed  magma,  after  diffu- 
sion through  water,  was  saturated  with  carbonic  acid  by 
allowing  the  gas  to  bubble  through  the  diffused  mass  for 
six  or  eight  hours,  or  longer.  After  this  treatment  the 
precipitate  was  again  well  washed,  and  then,  after  mixing 
with  water,  decomposed  by  sulphuretted  hydrogen,  the 
lead  sulphide  filtered  off,  and  the  resulting  dissolved  or- 
ganic matters  evaporated  to  dryness  at  a  gentle  heat  and 
weighed.  The  substance  thus  separated  was  heated  with 
Fehling's  solution  (Violette's),  near  the  boiling-point,  for 
some  minutes,  the  resulting  cuprous  oxide  converted  in  cu- 
pric  oxide,  and  weighed,  special  correction  being  made  for 
the  filter-ash  (page  203). 

The  results  are  given  below ;  .100  gramme  organic  matter 
of  the  different  origins  given,  caused  the  reduction  of  the 
following  amounts  of  copper  oxide : 

West  India  molasses 027  gramme  CuO 

Residual  syrup  from  sugar-refining  . .       .030        "          " 

Beet-molasses 0124      "          " 

Muscovado  raw  sugar 0246       "          " 

Manilla  "  t. 0170       "          " 

.100  gramme  invert-sugar  reduces. .       .2206       "          " 

In  order  to  test  whether  any  sugar  might  have  been  re- 
tained in  the  precipitates  before  decomposition  with  lead, 
a  control  experiment  was  made  by  adding  tartrate  of  soda 
and  potash  to  a  solution  of  pure  in  vert- sugar,  and  precipi- 
tating with  basic  acetate  of  lead.  This  produced  a  volumi- 
nous precipitate  similar  to  that  thrown  down  from  impure 
sugar  solutions.  The  tartrate  of  lead  was  treated  in  the 
same  manner  as  the  compounds  of  lead  and  organic  matter, 


NOTE.  337 

as  detailed  above,  and  the  tartaric  acid  obtained  after  the 
decomposition  with  sulphuretted  hydrogen  was  heated 
with  the  copper  solution. 

.100  gramme  reduced  .002  gramme  CuO. 

From  this  it  may  be  concluded  that  little  or  no  sugar 
was  retained  in  the  organic  lead  compounds  operated 
upon. 

As  a  general  result  of  these  experiments,  it  may  be 
proved  by  calculation  that  organic  matters  in  impure  su- 
gars have  too  small  an  influence  upon  the  results  of  the 
copper  test  to  make  it  necessary  to  remove  them  from  the 
sugar  solutions  in  most  cases.  When  the  saccharine  ma- 
terial contains  a  considerable  proportion  of  these  com- 
pounds, for  very  accurate  work  such  removal  may  be 
desirable. 


338 


APPENDIX. 


TABLES. 


I 


PARTIAL  LIST  OF  THE  ATOMIC  WEIGHTS. 


Symbol. 

Old. 

New. 

Al 
Sb 
As 
Ba 
Bi 
B 
Br 
Ca 
C 
Cl 
Cr 
Co 
Cu 
F 
Au 
H 

Fe 
Pb 

Mg 
Mn 
Hg 
Ni 
N 
0 
P 
Pt 
K 
Si 
Ag 
Na 
Sr 
S 
Sn 
Zn 

13-75 
122. 

75- 
68.5 

210. 
II. 
80. 
2O. 

6. 

35-5 
26.2 

29-5 
31-7 
19. 
196. 
1. 
127. 
28. 
103-5 

12. 

27-5 
IOO. 

29.5 
14. 

8. 

31- 
98.94 

39-i 
14. 

108. 
23- 
43-75 
16. 

59- 
32.5 

27-5 
122. 

75- 
137. 

210. 
II. 

So. 
40. 

12. 

35-5 
52.4 
59- 
63-4 
19. 
196. 
1. 
127. 
56. 
207. 
24. 

55- 
200. 

59- 
14. 
16. 

3i. 
197.9 

39-1 
28. 
108. 
23- 
87-5 
32. 
118. 
65- 

Arsenic     .                       ••      

Barium  

Boron     •           .  .  .  .    

Bromine.  ..   •  

Cobalt  

Gold  

Hydrogen  

Iron    

Manganese         ...... 

Mercury  «  

Nickel  

Nitrogen      ....       . 

Oxygen  

Platinum  

Potassium  

Silver  .... 

Sulphur  

Tin  

Zinc  

TABLES. 


339 


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340 


APPENDIX. 


III. 


TABLE  SHOWING  THE  RELATION  OF  TEMPERATURE,   DENSITY,  AND  DEGREES 
BAUME  of  SUGAR  SOLUTIONS  (FLOURENS). 


Temp. 

Per  cent,  of 
sugar. 

Baume, 

Density, 

At  obser.  temp. 

At  15°  C. 

At  obser.  temp. 

At  15°  C. 

0 

64.70 

35.30 

34.60 

1.3235 

I.3I50 

5 

65.00 

35-35 

34-9° 

I.3243 

I.3I90 

10 

65.50 

35.45 

35-00 

1.3255 

1.3225 

15 

66.OO 

35.50 

35.50 

1.3260 

1.3260 

20 

66.50 

35.60 

35-75 

I-3275 

1.3290 

25 

67.20 

35-80 

36.25 

1.3300 

1.3355 

30 

68.00 

36.00 

36.70 

1.3325 

1.3405 

35 

68.80 

36.20 

37.10 

1-3350 

1.3460 

40 

69.75 

36.40 

37.50 

1.3375 

I-35IO 

45 

70.80 

36.75 

38.10 

I.34IO 

1-359° 

50 

71.80 

37.10 

38.70 

1.3460 

1.3660 

55 

72.80 

37-50 

39-30 

I.35IO 

1-3740 

60 

74.00 

37-9° 

39.90 

1.3560 

1.3820 

65 

75-00 

38.30 

40.55 

I.36I5 

1.3910 

70 

76.10 

38.60 

41.10 

1.3650 

1.3980 

75 

77-20 

39-00 

41.70 

1.3700 

1.4060 

80 

78.35 

39-30 

42.20 

1.3740 

1.4130 

85 

79-50 

39.65 

42.80 

1.3790 

1.4220 

90 

80.60 

39-95 

43.30 

1.3820 

1.4290 

95 

81.60 

4O.IO 

43-70 

1.3850 

1.4300 

100 

82.50 

40.30 

44.10 

1.3875 

1.4400 

TABLES. 


341 


IY. 

TABLE  SHOWING  THE  RELATION  OF  DENSITY,  DEGREES  BAUME,  AND  BOILING- 
POINTS  OF  SUGAR  SOLUTIONS  (FLOURENS). 


Boiling  temp. 

Baume, 

Density, 

Per  cent,  of 
sugar. 

At  observed 
temp. 

At  15°  C. 

At  observed 
temp. 

At  15°  C. 

104.5 

32.20 

36.25 

1.2872 

1-3350 

67.25 

105. 

33-20 

37-25 

1.2990 

1.3480 

69.I 

105-5 

34.20 

38.30 

I.3I06 

I.36I3 

71.2 

106. 

35-00 

39.10 

I.32CO 

1.3720 

72.4 

106.5 

35-50 

39.65 

1.3260 

1.3780 

73-4 

107. 

36.00 

40.15 

1.3325 

1.3855 

74-4 

107-5 

36.50 

40.70 

1.3385 

1.3925 

75-2 

108. 

37-00 

4I.IO 

1-3450 

1.3985 

76-4 

108.5 

37.50 

41.75 

I-35IO 

1.4080 

77-4 

109. 

37-90 

42.IO 

1.3562 

I.4I2O 

77-8 

109.5 

38.25 

42.50 

1.3606 

1.4180 

78.7 

no. 

38.50 

42.80 

1.3640 

I.42I5 

79-5 

110.5 

33.75 

43-00 

1.3670 

1.4245 

80.0 

III. 

39-00 

43-30 

1-3700 

1.4290 

80.6 

in.  5 

39-30 

43-65 

1-3740 

1.4335 

81.4 

112. 

39-6° 

44.00 

1-3770 

1.4380 

82.2 

112.  5 

39-So 

44.20 

I.38IO 

I.44I5 

82.9 

113- 

40.00 

44.40 

I.3S35 

1-4500 

83.6 

114. 

40.30 

1.3875 

84.2 

US- 

40.60 



I-  39*5 



85.2 

116. 

40.90 



1-3955 



85.8 

117. 

41.20 



1.4000 

86.5 

118. 

41-45 



1.4030 



.   87.2 

119. 

41.65 



1.4060 

87.9 

120. 

41.90 



1.4085 



88.5 

125. 

42.80 

.... 

1.4215 



91.2 

130. 

43-50 

I.43I5 

.... 

92.2 

342 


APPENDIX. 


V. 


BOILING-POINTS  OF  SUGAR  SOLUTIONS  (AFTER  GERLACH). 


Per  cent,  sugar. 

Boiling-point,  C. 

IO. 

100.4 

20. 

100.6 

30. 

IOI.O 

40. 

IOI.5 

50. 

102.0 

60. 

IO3.O 

70. 

106.5 

79- 

112.  0 

90.8 

I3O.O 

VI. 


VOLUMES  OF  SUGAR  SOLUTIONS  AT  DIFFERENT  TEMPERATURES  (GERLACH). 


Temp.  C. 

10  per  cent. 

20  per  cent. 

30  per  cent.    40  per  cent. 

50  per  cent. 

0 

10000 

10000 

IOCOO 

1  0000 

10000 

5 

10004.5 

10007 

10009 

IQOI2 

IOOI6 

10 

1  001  2 

IOOI6 

IOO2I 

IOO26 

IOO32 

15 

1  002  1 

10028 

10034 

10042 

IOO5O 

20 

10033 

I004I 

10049 

I005S 

10069 

25 

10048 

10057 

IOO66 

10075 

10088 

30 

IOO64 

10074 

IOO84 

10094 

IOIIO 

35 

10082 

IOOQ2 

IOI03 

IOII4 

10132 

40 

IOIOI 

IOII2 

IOI24 

IOI36 

10156 

45 

IOI22 

IOI34 

10146 

IOI60 

10180 

50 

IOI45 

IOI56 

IOI7O 

10184 

10204 

55 

IOI70 

IOI83 

10196 

IO2IO 

10229 

60 

IOI97 

10209 

10222 

10235 

10253 

65 

10225 

10236 

IO249 

I026I 

10278 

70 

10255 

10265 

10277 

IO287 

10306 

75 

10284 

10295 

10306 

IO3I6 

10332 

80 

I03I6 

10325 

10335 

10345 

10360 

85 

10347 

10355 

10365 

10375 

10388 

QO 

10379 

10387 

10395 

10405 

10417 

95 

IO4II 

I04I8 

10425 

10435 

10445 

100 

10442 

10450 

10456 

10465 

10457 

TABLES. 


343 


VII. 

THE  AMOUNT  OF  LIME  CONTAINED  IN  MILK  OF  LIME  OF  VARIOUS  DEN- 
SITIES (MATEGCZEK). 


I  K.  CaO 

I  K.  CaO 

Degree  Baume. 

Degree  Erix. 

contained     in 
—  litres  milk 

Degree  Baume. 

Degree  Brix. 

contained    in 
—  litres  milk 

of  lime. 

of  lime. 

IO. 

18.0 

7-50 

21. 

38.3 

4.28 

II. 

2O.O 

7.10 

22. 

4O.2 

4.l6 

12. 

21.7 

6.70 

23- 

42.0 

4-05 

13- 

23-5 

6.30 

24. 

43-9 

3-95 

14. 

25-3 

5-88 

25- 

45-8 

3-87 

15- 

27.2 

5-50 

26. 

47-7 

3-81 

16. 

2Q. 

5-25 

27. 

49.6 

3-75 

17- 

30.9 

5.01 

28. 

51.6 

3.70 

18. 

32.7 

4.80 

29. 

53-5 

3-^5 

19. 

34-6 

4.68 

30. 

55-5 

3.60 

20. 

36.5 

4.42 

VIII. 

DENSITY  OF  LIME  SUCRATE  SOLUTIONS  (PELIGOT). 


The  sucrate  solution  contains  in 

100  parts  : 

Per  cent,  of  sugar. 

Density  of  sugar 

Density  when  satu- 

solutions. 

rated  with  CaO. 

CaO 

Sugar. 

40.0 

.122 

.179 

21.  0 

79.0 

37-5 

.116 

•175 

20.8 

79-2 

35-0 

.110 

.166 

20.5 

79-5 

32.5 

.103 

•159 

20.3 

79-7 

30.0 

.096 

.148 

20.1 

79-9 

27-5 

.089 

•139 

19.9 

80.  i 

25.O 

.082 

.128 

19.8 

80.2 

22.5 

•075 

.116 

19-3 

80.7 

2O.  O 

.068 

.104 

18.8 

81.2 

17-5 

.060 

.092 

18.7 

81.3 

15.0 

.052 

.080 

18.5 

81.5 

12.5 

.044 

.067 

18.3 

81.7 

IO.O 

.036 

•053 

18.1 

81.9 

5.0 

.027 

.040 

16.9 

83.1 

2.5 

.018 

.026 

15-3 

84-7 

344 


APPENDIX. 


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TABLES. 


345 


X. 


TABLE  SHOWING  THE   EQUIVALENCE   OF   THE  Centigrade  THERMOMETER 
SCALE  WITH  THAT  OF  Fahrenheit. 


c. 

F. 

C. 

F. 

C. 

F. 

-j-IOO 

+212. 

+63 

+145-4 

+26 

+78.8 

99 

2IO.2 

62 

143.6 

25 

77- 

98 

208.4 

61 

141.8 

24 

75-2 

97 

206.6 

60 

140. 

23 

73-4 

96 

204.8 

,59 

138.2 

22 

71.6 

95 

2O3. 

58 

136.4 

21 

69.8 

94 

201.2 

57 

134.6 

2O 

68. 

93 

199.4 

56 

132.8 

19 

66.2 

92 

197.6 

55 

131. 

18 

64.4 

9i 

195.8 

54 

129.2 

17 

'    62.6 

90 

194. 

53 

127.4 

16 

60.8 

89 

192.2 

52 

125.6 

15 

59- 

88 

190.4 

5i 

123.8 

14 

57-2 

87 

188.8 

50 

122. 

13 

55-4 

86 

186.6 

49 

1  20.  2 

12 

53-6 

85 

I85. 

48 

II8.4 

II 

51-8 

84 

183.2 

47 

II6.6 

10 

50. 

83 

l8l.4 

46 

II4.8 

9 

48.2 

82 

179.6 

45 

113- 

8 

46.4 

81 

177.8 

44 

III.  2 

7 

44.6 

80 

I76. 

43 

109.4 

6 

42.8 

79 

174.2 

42 

107.6 

5 

42. 

78 

172.4 

4i 

105.8 

4 

39-2 

77 

170.6 

40 

104. 

3 

37-4 

76 

168.8 

39 

102.2 

2 

35-6 

75 

I67. 

38 

IOO.4 

I 

33-8 

74 

165  .2 

37 

98.6 

O 

32. 

73 

163.4 

36 

96.8 

—    I 

30.2 

72 

161.6 

35 

95- 

2 

28.4 

7i 

159-8 

34 

93-2 

3 

26.6 

70 

158. 

33 

91.4 

4 

24.8 

69 

156.2 

32 

89.6 

5 

23- 

63 

T54-4 

3i 

87.8 

6 

21.2 

67 

152.6 

30 

86. 

7 

194 

66 

150.8 

29 

84.2 

8 

17-6 

65 

149- 

28 

82.4 

9 

15-8 

64 

147.2 

27 

80.6 

10 

14. 

346 


APPENDIX. 


XL 


TABLE  SHOWING  THE  EQUIVALENCE  OF  THE  Fahrenheit  THERMOMETER 
SCALE  WITH  THAT  OF  THE  Centigrade. 


F, 

C. 

F. 

C. 

F. 

C. 

-}-2I2 

-j-IOO. 

+170 

+76.67 

+128 

+53-33 

211 

99-44 

169 

76.11 

127 

52.78 

2IO 

98.89 

168 

75-55 

126 

52.22 

209 

98.33 

167 

75. 

125 

51-67 

208 

97.78 

1  66 

74-44 

124 

51.11 

207 

97.22 

165 

73.89 

123 

50.55 

206 

96.67 

164 

72.33 

122 

50. 

205 

96.11 

163 

72.78* 

121 

49-44 

204 

95-55 

162 

71.22 

1  2O 

48.89 

203 

95- 

161 

71.67 

IT9 

48.33 

2O2 

94-44 

1  60 

71.11 

118 

47-78 

201 

93.89 

159 

70.55 

117 

47.22 

2OO 

93-33 

158 

70. 

116 

46.67 

IQ9 

92.78 

157 

69.44 

US 

46.11 

I98 

92.22 

156 

68.89 

114 

45-55 

197 

91.67 

155 

68.33 

H3 

45- 

I96 

91.11 

154 

67.78 

TI2 

44-44 

195 

9°-55 

153 

67.22 

III 

43-89 

194 

90. 

152 

66.67 

no 

43-33 

193 

89.44 

151 

C6.li 

109 

42.78 

I92 

88.89 

150 

65-55 

108 

42.22 

I9I 

88.33 

149 

65. 

107 

41.67 

190 

87.78 

148 

64.44 

106 

41.11 

189 

87.22 

147 

63.89 

105 

40.55 

188 

86.67 

146 

63.33 

104 

40. 

187 

86.11 

145 

62.78 

103 

39-44 

186 

85.55 

144 

62.22 

IO2 

38.89 

185 

85. 

143 

61.67 

101 

38.33 

184 

84.44 

142 

61.11 

100 

37.78 

183 

83.89 

141 

60.55 

99 

37-22 

182 

83.33 

140 

60. 

98 

36.67 

181 

82.78 

139 

59-44 

97 

36.11 

1  80 

82.22 

138 

58.89 

96 

35-55 

179 

81.67 

137 

58.33 

95 

35- 

178 

8i.il 

136 

57.78 

94 

34-44 

177 

80.55 

135 

57-22 

93 

33-89 

176 

80. 

134 

56.67 

92 

33-33 

175 

79-44 

133 

56.11 

91 

32.78 

174 

78.89 

132 

55-55 

90 

32.22 

173 

78.33 

131 

55- 

89 

31.67 

172 

77.78 

130 

54-44 

88 

31.11 

171 

77-22 

129 

53.89 

87 

30.55 

TABLES. 


347 


XL  —(Continued. ) 


F. 

C. 

F. 

C. 

F. 

C. 

+86 

+30. 

+61 

+16.11 

+37 

+2.78 

85 

29-44 

60 

15-55 

36 

2.22 

84 

28.89 

59 

15. 

35 

1.67 

83 

28.33 

58 

14.44 

34 

I.  II 

82 

27.78 

57 

13.89 

33 

0.55 

Si 

27.22 

56 

13-33 

32 

o. 

80 

26.67 

55 

12.78 

3i 

o.55 

79 

26.11 

54 

12.22 

30 

—  i.  it 

78 

25.55 

53 

11.67 

29 

1.67 

77 

25. 

52 

II.  II 

28 

2.22 

76 

24.44 

51 

10-55 

27 

2.78 

75 

23.89 

50 

10. 

26 

3-33 

74 

23.33 

49 

9-44 

25 

3.89 

73 

22.78 

48 

8.89 

24 

4.44 

72 

22.22 

47 

8.33 

23 

5- 

7i 

21.67 

46 

7.78 

22 

5-55 

70 

21.  II 

45 

7.22 

21 

6.ii 

69 

20.55 

44 

6.67 

20 

6.67 

68 

20. 

43 

6.ii 

19 

7.22 

67 

19.44 

42 

5-55 

18 

7.78 

66 

18.89 

4i 

5- 

17 

8-33 

65 

18.33 

40 

4-44 

16 

8.89 

64 

17.78 

39 

3-89 

15 

9.44 

63 

17.22 

38 

3-33 

14 

10. 

62 

16.67 

XII. 

CHANGES  IN  VOLUME  OF  SUGAR  SOLUTIONS  WHEN  DILUTED  WITH  WATER 
(AFTER  GERLACH). 


Per  cent  of  sugar 
in  solution. 

Found  density  at 

17^°  c. 

Mean  calculated 
density. 

Volume  after  mix- 
ing. 

70 

.3507 

.3507 

1.  0000 

60 

.2900 

.28626 

.99710 

50 

.2329 

.22769 

•99577 

40 

.1794 

.17422 

.9956o 

30 

.1295 

.12521 

.99620 

20 

.0832 

.08013 

.99716 

10 

.0404 

.03852 

.99819 

O 

.0000 

.0000 

l.OOOO 

INDEX. 


PAGE 

Absorptive  power  of  bone-black 299,  301 

estimation  of 327,  332 

Acid,  acetic 42, 185,  211 

aconitic : 211 

aspartic 211,  251 

butyric 21,  211 

formic 183,  211 

glucic 81,  211 

gluconic..., 27,  88 

glutaminic 2^1 

gummic 185 

hexepic , 51 

hydrochloric 50 

isodiglycoethylenic 27 

lactic 21,211 

levulinic 49,  £8 

malic 2U,  251 

melassic 53,  £i,  211 

inetapectic 251 

mucic 27 

nitric 28,  93 

oxalic 50,  211 

oxymalonic 185 

racemic 27 

saccharic 27,  55 

sulphuric 28,  49 

tannic 251 

tartaric. 27,211 

trijienic 5I 

Acids,  reactions  of  sugars  wfth  . 28 

action  on  milk-sugar 94 

Adulteration  of  raw  sugar  with  dextrin 284 

Alcohol,  influence  on  results  in  polarizing . .  75 

method  of  extraction  by 180 

Alkalies,  action  on  sugars 29 

action  on  cane-sugar 54 

action  on  milk-sugar 94 

action  on  dextrose 7^ 

influence  on  results  in  polarizing 175 

Alkaline  salts  in  bone-black 307 

Alkaline  ash 225 

Alkalinity,  estimation  of 258,  272 

Alteration  of  char  by  use 304 

Alum  as  a  decolorizing  agent 164 

Alumina  as  a  decolorizing  agent 154 


Ammonia,  action  on  sugars 

action  on  cane-sugar 

action  on  dextrose 

Amylin 


PAGE 
30 
•54 
Si 
279 

Analyses  of  bone-black 296,  297,  310 

of  starch-sugar 278,  279 

of  sugar-ashes 223,  224 

Anhydrides  of  the  glucoses 12 

Animal  charcoal 296 

analysis  of 311 

chemistry  of 296 

Anthon's  method 282 

Apjohn 209 

Appendix 335 

Arabinose 14 

Areometer,  the 96,  100 

Areometers,  of  constant  weight 100 

of  constant  volume loo 

of  even  scale 101 

of  uneven  scale 101 

Ash,  estimation  of , 263,  270,  271 

estimation  in  raw  sugar 222 

estimation  in  molasses 252 

analyses  of 223,  224 

Asparagine 2=;i 

Assamar 16,  42 

Atomic  weights,  table  of 338 


Balling's  areometer. . 

Bardy  and  Riche 

Barfoed's  test 

Barley-sugar 

Barreswill 

Baume's  hydrometer, 
graduation  of. . 


no 

177 

85 

42 

185 

106 

107 

correction  for  temperature no 

Bdchamp  on  inversion 64 

Beet,  the 265 

estimation  of  sugar 266 

estimation  of  juice 270 

estimation  of  sugar  in  juice 271 

sampling  of 265 

Behr,  inversion  by  acids 46 

Berthelot 16,  28 


INDEX. 


340 


PAGE 

Betaine 9      212 

Biliary  acids 293 

Biot 15 

Birotation 18,  79 

Eoivin  et  Loiseau  59,  284 

Bodenbender .'  301 

Boiling-points  of  sugar  solutions 341,  342 

Bone-black  as  decolorant 167 

absorption  of  sugar  by 168 

analyses  of 296,  297,  310 

absorbing  power  of 299,  301 

alteration  by  use 304 

alkaline  salts  in 307 

density  of,  absolute 327 

density  of,  apparent 326 

nitrogen  in 309 

washing  and  burning  of 333 

Borax  combined  with  sugar 63 

Borneite , 14 

Borneosc 14 

Brix  areometer 1:2 

correction  for  temperature 114 

error  of 112 

Bromine,  action  on  sugars 27 

Buignet 16,  33 


Calcimeter,  Scheibhr's 

Cane,  the 

estimation  of  sugar  in 

Cane-juice,  estimation  of  sugar  ia. 


313 
260 
260 

25l 

Cane-sugar,  determination  of 120 


in  raw  sugar 211 

estimation  in  raw  sugar 213 

estimation  in  molasses 250 

occurrence  of 31 

estimation  in  dilute  solutions 276 

Caramel 43 

-Carbohydrates 10 

Carbon  in  bone-black 306 

estimation  of 311 

Carbonate  of  lime  in  bone-black 306 

estimation  of 313 

removal  by  acid 318 

Casamajor's  mod.  of  Dumas's  method 248 

method  for  quotient 254 


Champonnois's  rape 265 

Chancel  on  contraction  by  inversion 90 

Chandler  and  Ricketts's  method 287 

Charbon  d'os 296 

Chlorine,  action  on  sugars 27 

on  cane-sugar 51 

Chylariosc £7 

Centigrade  and  Fahrenheit  scales 346 

Circular  polarization 122,  179 

Clerget's  method 136 

table  I3g 

Coefficients,  method  of. 237 

Collier  on  the  sorghum 31 

Colloidal  water 2-o 


PAGE 

Color,  estimation  of 229,  258,  272 

estimation  by  Duboscq's  colorimeter.  329 

Colorimeter,  Stammer's 223 

Duboscq's 329 

Colorimetry  after  Monier 233 

Compounds  of  dextrose £3 

Contraction  in  sugar  solutions 40,  90 

Copper  oxide  hydrated,  action  on  sugar. ...  26 

Copper  sulphate  for  Fehling's  solution 199 

Corenwinder's  method 332 

Corn-sugar 278 

Correction  for  temperature no,  113 

Correction  of  measuring  apparatus 177 

Courtonne  on  the  solubility  of  cane-sugar. .  39 


Dambose 

Dambonite 

Decolorization  of  sugar  solutions 

Decolorizing  power  of  char 

Densimeter,  the 

Detection  of  starch-sugar  in  cane-sugars. . . 
Determination  of  cane-sugar 

method  of  Peligot 

by  alcohol. 

by  fermentation 

by  inversion  and  Fehling's  method.. .. 
Determination  of  dextrose  and  invert-sugar 

by  Fehling's  method 

Dextran 

Dextrin  as  an  adulterant  of  raw  sugars 

Dextrose. . . , 


preparation  from  starch 

preparation  from  urine 

properties 

solubilities 

action  of  heat  on 

action  of  acids  on 

action  oi  alkalies , 

action  of  cupric  salts 

various  reactions 

combinations 

combination  with  water 

combination  with  bases 

combination  with  sodium  chloride. . . . 

qualitative  test  for,  in  urine 

Diabetic  sugar 

estimation  of 

Diabetooeter 

Diastase 

Double-dilution,  method  of 

Di-glucosic  alcohols 

Duboscq's  shadow  saccharimeter 

colorimeter 

Durin,  cellulosic  fermentation 

Dulcite 

Dumas's  method 

Dupre 


14 
14 
iS* 

328,  332 
i°5 
284 

120,  179 
179 
ifo 

181 
182 

185 
251 
284 
74,75 
75 
76 

77,78 
77 
79 
80 
82 
82 
Si 
£3 


Eissfeldt  and  Follenius. 


84 
294 

74 
292 
293 

15 
i57 

II,  12 
157 
329 
25 
14 
247 
2CX) 


351 


350 


INDEX. 


Elliptical  polarization 

Errors  of  optical  method . 

by  temperature 

personal  error 

from  presence  of  invert-sugar 

from  use  of  lead  solution 

from  volume  of  lead  precipitate 

Erythromannite 

Erythrozyme 

Eucalyn 

Exponent  of  sugar  solutions 


Fahrenheit  and  Centigrade  scales,  table  of. 

Fehling 

Fchling's  method  for  estimation  of  dextrose 
and  invert-sugar 

for  estimation  of  cane-sugar 

for  exact  work 

for  starch-sugar 

for  milk-sugar 

Fehling's  solution 

Fermentation,  estimation  of  cane-sugar  by. 

analysis  of  starch-sugar  by 

influence  of  saline  matters  on 

butyrous 

cellulosic 

lactous 

mucous 

vinous 

Filter  ash  for  Fehling's  method 

Filtering  cylinder 

Flourens's  tables 

Formation  of  sugar  in  plants 

Fruit-sugar 

Four-fifths  method. . . 


G 


Galactose 14 

Gay  Lussac's  volumeter  103 

Gcntele's  method 210 

Gcrlach 340,342,345 

' 165, 174,  196 


122 
170 
170 
I70 
173 
165 

166 
14 
95 
14 

253 


347 

i£5 

185 
182 

201 
280 
290 
I87 

181 
281 
24 
19 
25 
19 
18 

21 
204 
215 

340,  341 
15 

74,87 
217 


Girard,  preparation  of  levulose 

Girard  and  Laborde 

G  lucose  normal  solution 

Glucose 

Glucoses,  the 

Glutaminicacid... 


87 

173 

191 

74,  278 

II 
251 


Grape-sugar 74,  278 

Gravimetric  estimation  by  Fehling's  method  203 

Gunning  on  the  melassigenic  action  of  salts  60 


II 


TIarnzuckcr 

Heat,  action  0:1  sugars 

Hesse  on  sp.  rot.  power  of  lactose 

Ilexatomic  alcohols 

Ilochstetter  on  inversion  by  heat. . . 


Honey-sugar 

Honigzucker 

Horneman , 

Hundert  polarization , 

Hydrometer,  Baume's 

Hydrostatic  balance,  the , 


leery 

Inactive  cane-sugar 

Influence  of  various  bodies  on  polarization. 
Inosite 

hex-nitro 

Insoluble  matter,  estimation  of,  in  raw 

sugars 

Inversion  of  sugars 

Inversion  of  cane-sugar  by  heat 

by  acids 

byC02 

by  sulphurous  acid 

Invert-sugar 

optical  inactivity  of 

estimation  of. 

Invertin 

Iron  in  bone-black 

estimation  of 

Isodulcite. .. , 


J 


Jackson 

Jellett 

prism,  the 

Juice  beet,  estimation  of 


Knapp's  method 

Knochenkohle 

Kornzucker 

Krumelzucker 


PAGE 

74 
87 
27 
150 
zo6 
96 


16 
73 
173 
14 


235 
129 
43 
45 
43 
49 
*9 
173 

185,  217 

23 

3^7 

323 

14 


155 

IS7 

269,  270 


206 
296 

278 
74 


Lactate,  calcium 

Lactin,  lactose 

La  Grange  on  the  melassigenic  action  of 

salts 

Lamp,  oil 

Laurent's  monochromatic 

Landolt  on  personal  error 

Laurent's  saccharimeter 

monachromatic  lamp 

Lead  acetate,  basic,  preparation  of 

Lead  precipitate,  error  from 

solution,  experiments  on  error  caused 

by , 

Left-rotating  bodies 

Levulinic  acid 

Levulosc,  decompositions 

preparation  of 

properties 

Light,  monochromatic  or  sodium 


7° 
151 
1 54 
172 

159 
154 

US, 

i65 

165 

125 

49,^7 

87,  £3 

£7 


INDEX. 


351 


Lime,  action  on  cane-sugar 

Lindo's  test 

Linksfruchtzucker 

Lowig 

Lotman • 

Lowenthal  and  Lenssen  on  inversion. . . 


M 


Malic  acid 

Maltose 

Malus  on  the  laws  of  polarized  light 

Mannite  

Mannitose 

Marc,  estimation  of  sugar  in 

Marc,  estimation  of  in  the  beet,  by  direct 
method 

by  indirect  method 

after  Scheibler 

Marcker 

Marks  of  a  good  char 

Marschall  on  the  melassigenic  action  of 

salts 

Mategczek 

Maumene 

Mazzara's  test 

Measuring  apparatus,  correction  of 

Meissl  on  inactive  invert-sugar 

Meissl 

Melezitose 

Metapectic  acid 

Melassigenic  action 

Metezose 

Metezite 

Milchzucker 

Milk,  carbohydrates  from 

Milk-sugar,  estimation  of 

Milk-sugar,  specific  rotatory  power 

hydrates 

combinations 

solubilities 

action  of  heat 

action  of  acids 

fermentation  of 

Milk  of  lime,  contents  of,  in  CaO 

Mitscherlich's  saccharimeter 

Mohr's  method  for  dextrose 

Monier's  copper  solution 

Morin  on  inactive  invert-sugar 

Muffle  for  ash  estimation 

Muntz 

on  inactive  invert-sugar 

Mycose 

Mycoderma  aceti 


N 


Neubauer 186,  281,  295 

on  estimation  of  dextrose  and  levulose  208 

Nichol's  prism 122 

Nitrogen  in  bone-black 299,  309 

Nucite...  Ti 


55* 
86 

87 
17 

247 
43 


25,1 
14 
123 

M 

14 
275 

269 
269 
270 
204 
303 

69 

343 

24.43 

86 

177 

174 

203 

14 

251 

64 

14 

14 

£1 

54 
290 

91 
52 

92,  94 
$2 
52 
93 
95 
343 
126 
205 

•  Ig7 
173 
227 
176 
173 
14 


o 

PAGE 

Organic  matter,  action  on  Fehiing's  solution  335 

estimation  by  difference 233 

estimation  after  WalkofF. 234 

estimation  by  lead  subacetate 235 

estimation  in  molasses 253 

estimation  inbeet-juice 271 

Optically  inactive  invert-sugar 173 

Optical  saccharimeters 126 

rotatory  power  of  sugars 17 

Oxygen  and  air,  action  on  cane-sugar-. 52 

Oxidizing  agents,  action  on  sugars 26 

action  on  cane-sugar 50 


Faradextrose 86 

Parasaccbarose , 72 

Pasteur 19,  20,  22,  24 

Pavy's  modification  of  Fehiing's  method ...  210 

Payen-Scheibler's  process  for  yield 240 

Peligot 1 7, 179,  343 

Pellet 66,176 

Penicilium  glaucum 20 

Personal  error 170 

Phosphate  of  lime,  estimation  in  char 322 

Picric-acid  test  for  dextrose £6 

Finite 14 

Plagne 19 

Plane  of  polarization 121 

rotation  of 123,  124 

i5 
1 20 

121 
122 
122 
125 
I89 

31 

260 
170 


Pohl  , 

Polarized  light  by  reflection 

by  refraction 

Polarization,  elliptical 

circular 

Polariscope,  the 

Possoz's  copper  solution 

Popp,  analyses  of  sugar-cane 

Press,  cane 

Pure  sugar,  preparation  of 


Q 

Qualitative  tests  for  cane-sugar 52,  S3 

tests  for  dextrose 85 

Quercite 14 

Quotient  of  purity 253,  271 


Raffinationwerthes 

Raffinose 

Rag-sugar 

Reichenbach , 

Rcnard  

Rendcments 

Residues,  carbonatation 

Revivification  of  char , 

Rhamnegite 

Richard 

Right-rotating  bodies 

Right-handed  sugar 


74 
16 
17 
240 
275 
3°3 
14 
15 
126 
74 


352 


INDEX. 


Rodewald  and  Tollens. . , 
Rohrzucker 


Saccharose 

Saccharum  cfftcinarutn 

Saccharin 

Saccharides 

Saccharimeters,  Duboscq's  shadow 

Laurent's 

Mitscherlich's 

shadow 

Soleil-Duboscq 

Soleil-Ventzke 

Schtnidt-H  ansch 

Wild's 

Saccharimeters,  equivalence  in  degrees  of 

various 

Saccharometer,  Vivien's 

Balling's  or  Erix 

Saccharomyces  ceremsia 

Sachsse's  method 

Salts  in  raw  sugar. 

combination  of  cane-sugar  with 

invcrtive  action  of 

action  on  crystallization  . 

solubility  in  sugar  solutions 

Sampling  of  raw  sugars 

Scheiblcr's  modification  of  Payen's  process 
method  for  estimating  the   sugar  in 

the  beet 

method  for  estimating  the  sugar  in 

marc 

calcimeter 

improvements  on  the  Soleil-Ventzke 

saccharimeter 

Scheibler  on  the  solubility  of  cane-sugar  in 

aqueous  alcohol 

Schleimzuckcr 

Schmitt's  test  for  dextrose 

Schmidt   and  Hansch's  shadow  sacchari- 
meter  

Schmitz,    formula    for    specific    rotatory 

power  of  cane-sugar 

Scheme  for  ash  analysis 

Schultz  on  absorbing  power  of  bone-black.. 

Scums,  refinery 

Scyllite 

Senkwage 

Sensitive  tint 

Shadow  Saccharimeters 

Sickel 

Sodium  chloride,   combination  with  cane- 
sugar 

with  dextrose 

Soleil-Duboscq  saccharimeter 

Soleil-Ventzke  saccharimeter 

Soluble  ash 

Sorghum  Holcus 

Sorgl:i;:n  sacckaratum 

Sorbite 


PACE 

230 


3i 
3i 
17 
28 

156,  159 
159 
126 
156 
133 


^ 
US 
ISO 

23 

207 

211 


Sorbose 

Sostman 

Soxhlct 186,  201, 

Specific  gravity  of  bone-black,  absolute 

apparent 

Specific-gravity  flask,  the 

Specific  gravity,  determination  of 

Specific  rotatory  power 

Stammer's  colorimeter 

Starch-sugar 

Starkezucker 

Steiner's  analyses  of  starch-sugar 

Sucrate  of  lime  solutions,  table 

Sucrates 


of  calcium 

of  potassium 

of  sodium 

of  barium 

of  copper 

of  lead 

of  strontium 

of  iron 

of  magnesium 

Sucre  de  canne 


Sucre  de  fecule 

Sucre  delait 

Sucre  derasin 

Sucroscs 

Sucro-carbonate  of  lime 

Sugars  as  a  class 

Sugar,  common 

crystallizable 

in  the  nectar  of  flowers. 

in  roots 

in  the  beet 

in  stems  of  trees 

in  leaves 

in  fruits. . .  


in  manna 

preparation  from  natural  sources. 

preparation  of  pure 

physical  properties 

crystallization  of: 

density 

specific  rotatory  power 

endosmose 

composition  of 

action  of  light  on 

solubilities 

solutions,  tables  of 

action  of  heat  on 

inversion  of,  by  heat 

inversion  of,  by  acids 

action  of  alkalies  on 

combinations  with  salts 

melassigenic  action  on — 

in  bone-black,  estimation  of 

Sulphate  of  lime  in  bone-black 

estimation  of 

Sulphatcd  ash 

Sulphide  of  calcium  in  bone-black 

estimation  of  . .  


PAGE 
14 

175 

203,  290 
327 

56,98 

124 
229 

74,  278 

278 
278 
343 

56 

55,  56 
56 
60 
61 
60 

•      61 

61 

62 

31 

278 

91 

74 

14 

£9 

9 

3i 
32 
32 
32 
32 
32 
33 
34 
34 

I/O 

35 

36 

37 
39 
39 
38 

39,41 
339,  340 
41 
43 
45 
54 
62 
64 
325 
307 
320 
226 
308 
321 


INDEX. 


353 


Sweetness,  relative,  of  cane-sugar  and  dex- 
trose  

Sweet  taste  of  sugars , 

of  metallic  salts 

Synanthrose 

Synthesis  of  sugars 


Table,  Clergct's 

Tables  for  Scheibler's  calcimeter 317,  319 

Table  of  densities  and  degrees  Baume 109,  no 

for  Balling's  areometer 114 

of  reciproca's 193 

of  atomic  weights 338 

of  temperatures  and  concentrations. .  33(5,  340 
of  boiling-points  for  sugar  solutions. .  341,  342 
of  the  volumes  of  sugar  solutions  at 

various  temperatures 342 

showing  CaO  in  milk  of  lime 343 

showing  weight  of  a  cubic  foot  ar.d 

gallons  of  sugar  solutions 2\\ 

of  Centigrade  and  Fahrenheit 345 

of  Fahrenheit  and  Centigrade 346 

showing  relation  of  percentages,  den- 
sities, and  degrees  Baume  of  sugar  • 

solutions.. 116 

showing  relation  of  degrees  Baume, 
percentages,  and  densities  of  sugar 

solutions 119 

Tannin  in  polarization 251 

for  estimation  of  organic  matter 234 

Tollens,  formula  for  specific  rotatory  power 

of  cane-sugar 37 

Torula  accti ., 21 


ddex- 

Trehalose 

9 

Trommer  

u 

Urine,  estimation  of  sugar  in  

V 

16 

«a 

Ventzke's  saccharimeter 

process  for  sugar  estimation 

Violette's  solution 

Vivien's  saccharometer 

Volumeter  of  Gay  Lussac 

Volumes  of  sugar  solutions  at  various  tem- 
peratures         

w 


PAGE 

74 
14 

185 
75 


130 
261 


103 

342 


Walkoff  on  the  absorbing  power  of  bone- 
black  300,  302 

Walkoff  s  method 234 

Wallace  on  the  composition  of  char 296 

Waste  products,  analysis  of 273 

waters 276 

Water,  estimation  of 217,  252,  264,  270,  271,  283 

in  bone-black 311 

Weighing  capsule 213 

W'ild's  polaristrobometer 152 


Yeast 

Yield,  estimation  of , 


22 
237 


_  7 


THE  UNIVERSITY  OF  CALIFORNIA  LIBRARY 


